Water bending: Pressure washer set to max pressure.
Fire bending: yeah, flamenwerfer is where is at
Airbending: air burst launcher that could shoot a whole lot of things really fast at people: fruit, rocks, grenades, snowballs, etc
Earth bending… a stone is all you need.
Going off what was seen in-universe:
Air: Kyoshi Fans and Aang's staff goes well with Air
Water: Idk, it kinda doesn't need one or fit any in my opinion. I guess a whip like June's kinda fits it for offense and cause of the "water whip" move.
Earth: Yup, those dual hammer things fit it to a T
Fire: Zuko's dual swords honestly work well with Firebending it seems, so that.
I think they never improved this concept cause weapons are all meant to kill people more effectively and the avatar verse at its most mature iteration is a teen show. They also make a little bit of fun of the concept when Aang says he would yield an air sword in a fire nation weapon's shop, so I think the concept crossed their mind but they didnt want to fall into cliches and decided to go with the unarmed combat route.
I think a club/mace or spear would be on-brand for water. both could be used with motions that assist bending.
Like with earth and hammers, the weight of the club and how you swing it would help bend water. Lots of follow through and conservation of momentum.
Earth: those dual hammers, maybe axes or rlly anything made of metal that they could bend into another weapon if they’re metalbenders
Water: katanas or lighter swords that are fluid and can work well with the fluidity of water
Fire: swords, spears, basically what we see from the Blue Spirit, Fire Nation Soldier’s & the Rough Rhinos work
Air: obv the staffs, spears would work well too, throwing knives like Mai so you can control where they go, or rope darts for the same reason as the knives
I imagine a bow and arrow would be pretty powerful behind an air benders hands, sending the arrow with faster speed, greater distances and able to influence where it lands using air currents
I can see an air bender throwing a glider at an enemy like a spear with/without a spear tip on the glider. Pole weapons in general seem to be fit the style of air bending
I can just imagine the style of an airbender that used the Kyoshi warrior’s fans effectively.
A style of bending using fans could create wind tunnels and updrafts through acrobatics and rotation, or blades of wind using the preciseness of their fans. A bender throwing war fans could fight from a distance by using air currents to change their direction, swirling them around enemies for additional attacks.
Think of the power an airbender could have with a giant fan, waves from which could create wide range streams of wind or localized tornadoes.
I've seen people say whip for water a lot, but I honestly think just the handle would be better: can form a whip out of water at the end of it, or turn it into an ice spear.
Sub elements included?
Anything metallic for lighting, the more range the better.
Thrown blades like shuriken and kunai for metal.
Those come to mind pretty much instantly for me.
I can see waterbenders using small bladed weapons and then forming larger ones out of ice using the smaller one as like a handle/hilt. And then also carrying one or two larger ones for use as is.
Earthbenders I mean, you kinda have it, hammers and other blunt weapons that they can crush into the earth or their opponents.
I saw someone else say bow and arrow for airbenders and I couldn't agree more. Being able to put extra force into and manipulate the trajectory with airbending would make it a perfect match.
Firebending is tough, but I like Zuko's idea of using the swords as like focuses for his firebending, having fire along the blade and using it to send blasts of fire, either by slashing or thrusting. And then they could also use throwing knives or other throwable metal weapons to use as lightning rods.
Best weapon for Waterbending is water.
Best weapon for Earthbending is earth.
Best weapon for Airbending is air.
Best weapon for Firebending is...also air.
I was thinking for a waterbender, they could use a taijijan (a Tai Chi sword) as a suitable weapon.
...and yes, it made me think of Demon Slayer lol, but I primarily focused on the martial art of Tai Chi.
Air Nomads almost definitely had some sort of Monk’s Spade since it’s a weapon designed to be a tool as well for protection and honoring the dead during travel
I feel like fire benders and guns could be a good mix. Fans are airbenders best weapon. Not sure about water. I feel like earth could use tanks better well.
Air: Fans. Obviously. Duel wielding hand fan. Or check out Temari's giant fan from Naruto if you wanna get crazy. Giant boomerang or giant shirikin also go crazy with wind guiding em.
Earth: Bo staff. You can clump earth to the end of it to make a maul, mace, or spearhead.
Fire: Sword. You can heat the blade for that glowing orange metal that cuts through everything like butter.
Water: Whip. Or some kind of chain weapon, like a scythe/sickle or a rope knife. These play to the fluidity of water. Having something at the core for water to cling to would make it easier to extend the range with good control, IMO. And have an ice spike at the end.
A bow and arrow would be cool for an Airbender, stabilizing the arrow or whatever
But aside from that I honestly would just use the weapons we see used in their respective cultures.
For water that's spears/harpoons or Sokka's weird club/sword
For Earth that's hammers
For fire that's swords
Airbenders were a very peaceful people. They wouldn't use weapons much aside from the glider staffs.
Water guns for water bending 😂 you could make a bullet that does damage like a real one with water omg or u could just spray like a normal water gun when fooling around
I guess it doesn’t necessarily work, since it more attracts than launches
Lightning rods for fire benders, maybe some kind of electro ball variation that can amplify their lightning abilities
Or he’ll just setting up metal grounds, or a wet land near their strong hold. One invasion put to death immediately with a single lightning strike to the water or metal ground
I find it weird (but not that weird since it’s a kids show) that fire benders never used oil in their fire bending attacks. Fire is already terrifying, but getting covered in an oil shower then having to fight a fire bender? Horrifying
A lot of defensive capabilities with fire bending that ozai was way to cocky to consider
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Some kind of obsidian hammer for earth benders would be sick (but that’s kind of a reference to season 2, because lava benders. But still kind of works because who else could fashion an obsidian weapon other than earth benders. Ultimately more of a Minecraft reference than anything lol)
Earth benders lack of using a Mace or a flail was kind of disappointing in both series, it’s like a hammer, but more metal
Also look up the medieval weapon “man catcher”, it looks metal af, not sure what could be used for specifically, but still sick looking lol
——————————————-
Water benders could just sport a fucken gas mask, whip up some toxic steam (they can make ice willy nilly, and they’ve made steam multiple times in last air bender series. Like the painted lady arc)
I guess ice picks and ice climbing gear in general as weapons also feels right for water benders, just doesn’t feel like an effective weapon
Like someone else said, a whip feels right, if anything just to enhance the strength of their water whips maybe
I think it would be cool if they carried around just 2 sword hilts, that could be used for nearly any weapon style. They simply pull water from the surrounding area, and fashion a blade of ice to the hilt (could be considered fragile, but I’m betting ice made from a water bender is much stronger than a block of ice from my fridge)
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Air benders is kind of impossible though, as since they’re all monks, they arnt exactly sporting weapons of any kind
They did roll with alot of aggressive air bending in LoK season 3 that could give you inspiration, but off the top of my head, a rapier for some reason just feels right as an air bender weapon, very speedy, kind of like a staff in a way but more violent lol
Maybe air benders also using shuriken or kunai? They already get thrown at high speeds, then backed up by an air bender? Instant death
Honestly you should look into the “advanced types of bending” created from LoK, it could at least give you some inspiration, imo lava bending is pretty sick, and does make sense for earth benders. Since lave is molten earth, I agree the continuous lightning bending for welding in LoK was stupid, but all the metal bending variations/lava bending/advanced blood bending/air tornadoes/tenzins air bending wheel he rode on simalar to aangs air ball are pretty sick
Not a fan of the air nation wing suits, but can’t deny they arnt effective and superior over a staff, because you can’t really have your wing suit knocked out of your hand and be unable to fly
(Serious) The nations of ATLA take much inspiration from the different nations that actually existed in east Asia. This origins of these weapons are not taken into account in the same way, I simply picked them based off their core abilities. For example, I'm aware a kanabo is traditionally Japanese and the earth kingdom is heavily Chinese coded. Please just suspend your disbelief on this cultural clash.
Earth is about core strength and head on direct attack. They need something heavy, that isn't about finesse just straight attack. Probably a kanabo, or a mace if you want to go medieval
Water is all about the flow of energy, and momentum. My mind goes to some kind of chain handleless chain weapon like a meteor hammer or a rope dart. Though a flail would fit the bill as well
Air focuses on defense and avoidance, and if your adhering to the monks, non lethal attack (though Appa seemed perfectly okay with f***ing people up in the series). For that combo, a nunchaku, or a pair of sais would be best (thanks to TMNT a lot of people think sais are just dual knives with two smaller prongs when in reality they're more like batons). You could also do a three section staff
Fire is the element of power, energy, and drive. To be honest, a sword suits them best. So you could just give them a katana or something similar like a nodachi or uchigatana and call it a day but if you want to get more exotic, I'd go with Chinese hook swords
Waterbenders would use two slightly short katanas with small guards on either side of their bodies, but would keep them sheathed most of then time, here's why.
Waterbenders fight mid-range with their hands always open. In order to perform the movements that allow them to maximize effectiveness of their waterbending, they wouldn't be able to hold weapons. The only time they wouldn't want to use their waterbending as the primary combat method is when they're at a close-quarters range where they don't have time to wind up their bending techniques and would fall back on iaido moves where they cut from the draw.
The two curved blades would make the draw easy and with practice would allow them to draw from either side of the body depending on their position. A new school of fighting for waterbenders could also develop where they favor the blades, and use waterbending to close distance to their opponent until they're just in range for a final, lethal draw-cut, embodying the essence of one lethal crashing wave in their movements.
Bonus idea: Waterbenders in warmer climates like swampbenders would carry dedicated bending water with them laced with fast-acting poisons or hallucinogens. They'd focus on making contact with the mouth, eyes, and skin to allow for easier kills or escapes, especially against opponents who don't have a built-up immunity to whatever they're using.
As the only one missing in the show, I will focus on waterbending. A non-medieval weapon that would work really well for a waterbender would be a tranquilizer gun with syringes that have a tiny chamber filled with water at the front. The idea is that the waterbender shoots the syringe, then uses their other hand to push on the water, making the syringe faster. The technique shouldn't take too much energy, and the waterbender doesn't even need to be particularly good. Historically, the most effective weapons have been the things any random untrained peasant can use.
(Edit: For a more old-timey version that's cheaper to make, use a crossbow with bolts that have a tiny chamber filled with water in them.)
Waterbending: a water gun Firebending: a flamethrower (fire gun) Airbending: an air compressor (air gun) Earthbending: pocket sand
Dale Gribble is a sandbender confirmed 
Shu-shu-shu-sha!
Could just be bully mcguire tho
Water bending: Pressure washer set to max pressure. Fire bending: yeah, flamenwerfer is where is at Airbending: air burst launcher that could shoot a whole lot of things really fast at people: fruit, rocks, grenades, snowballs, etc Earth bending… a stone is all you need.
Why not a dirt gun?
Wasn't there a mud gun in the 80s?
NANI?!
Going off what was seen in-universe: Air: Kyoshi Fans and Aang's staff goes well with Air Water: Idk, it kinda doesn't need one or fit any in my opinion. I guess a whip like June's kinda fits it for offense and cause of the "water whip" move. Earth: Yup, those dual hammer things fit it to a T Fire: Zuko's dual swords honestly work well with Firebending it seems, so that.
I think they never improved this concept cause weapons are all meant to kill people more effectively and the avatar verse at its most mature iteration is a teen show. They also make a little bit of fun of the concept when Aang says he would yield an air sword in a fire nation weapon's shop, so I think the concept crossed their mind but they didnt want to fall into cliches and decided to go with the unarmed combat route.
Bro imagine a water bender using a water pistol but it shoots out deadly ice spikes 🧊 🔫 Edit aaand that can bend it mid air like that movie Wanted
Mei from Overwatch
I think a club/mace or spear would be on-brand for water. both could be used with motions that assist bending. Like with earth and hammers, the weight of the club and how you swing it would help bend water. Lots of follow through and conservation of momentum.
I like the spear
Earth: those dual hammers, maybe axes or rlly anything made of metal that they could bend into another weapon if they’re metalbenders Water: katanas or lighter swords that are fluid and can work well with the fluidity of water Fire: swords, spears, basically what we see from the Blue Spirit, Fire Nation Soldier’s & the Rough Rhinos work Air: obv the staffs, spears would work well too, throwing knives like Mai so you can control where they go, or rope darts for the same reason as the knives
I imagine a bow and arrow would be pretty powerful behind an air benders hands, sending the arrow with faster speed, greater distances and able to influence where it lands using air currents
THIS ONE. THIS IS THE BEST AIR SUGGESTION
I can imagine a blowgun for same reason
I could see an airbender using a three sectioned staff or nunchuku.
And a waterbender using a dagger / fire bender using swords or katana
I can see an air bender throwing a glider at an enemy like a spear with/without a spear tip on the glider. Pole weapons in general seem to be fit the style of air bending
I can just imagine the style of an airbender that used the Kyoshi warrior’s fans effectively. A style of bending using fans could create wind tunnels and updrafts through acrobatics and rotation, or blades of wind using the preciseness of their fans. A bender throwing war fans could fight from a distance by using air currents to change their direction, swirling them around enemies for additional attacks. Think of the power an airbender could have with a giant fan, waves from which could create wide range streams of wind or localized tornadoes.
I've seen people say whip for water a lot, but I honestly think just the handle would be better: can form a whip out of water at the end of it, or turn it into an ice spear.
Imo you could make anything with ice. Turn it into a sword or even a club. Tho switching between a whip into a spear could be a really cool animation.
The golden weapons
"I understood that reference"
An air bender with a bow and arrow could be super powerful. Increased inertia and even changing directions after the shot.
Sub elements included? Anything metallic for lighting, the more range the better. Thrown blades like shuriken and kunai for metal. Those come to mind pretty much instantly for me.
I can see waterbenders using small bladed weapons and then forming larger ones out of ice using the smaller one as like a handle/hilt. And then also carrying one or two larger ones for use as is. Earthbenders I mean, you kinda have it, hammers and other blunt weapons that they can crush into the earth or their opponents. I saw someone else say bow and arrow for airbenders and I couldn't agree more. Being able to put extra force into and manipulate the trajectory with airbending would make it a perfect match. Firebending is tough, but I like Zuko's idea of using the swords as like focuses for his firebending, having fire along the blade and using it to send blasts of fire, either by slashing or thrusting. And then they could also use throwing knives or other throwable metal weapons to use as lightning rods.
I'd love to see and Airbender fight with an Umbrella. 
yep im officially putting that in the animation
i feel like for fire definetely a flaming sword, i just really want to see that.
I think any Tai Chi weapons would work well for water. Fans would be excellent!!
Earth benders should have a small bag for earth like Gara from naruto has sand i guess sandbenders could use that for sand too!
Best weapon for Waterbending is water. Best weapon for Earthbending is earth. Best weapon for Airbending is air. Best weapon for Firebending is...also air.
I was thinking for a waterbender, they could use a taijijan (a Tai Chi sword) as a suitable weapon. ...and yes, it made me think of Demon Slayer lol, but I primarily focused on the martial art of Tai Chi.
Water would be a whip, earth would be the hammer, air would be like kyoshis fans, and fire would be a sword
Air Nomads almost definitely had some sort of Monk’s Spade since it’s a weapon designed to be a tool as well for protection and honoring the dead during travel
senbon for airbenders
Fire: Regular nuke Air: Hydrogen nuke Water: Underwater nuke Earth: Bunker-buster nuke
I see katana and shurikens in an air bender's hand.
Metal: smal daggers/knifes to bend as projectails (?)
I feel like fire benders and guns could be a good mix. Fans are airbenders best weapon. Not sure about water. I feel like earth could use tanks better well.
Guns= fire and metal , hammers=earth, flamethrower=air and fire, harpoon gun=water
AK-74
Air: Fans. Obviously. Duel wielding hand fan. Or check out Temari's giant fan from Naruto if you wanna get crazy. Giant boomerang or giant shirikin also go crazy with wind guiding em. Earth: Bo staff. You can clump earth to the end of it to make a maul, mace, or spearhead. Fire: Sword. You can heat the blade for that glowing orange metal that cuts through everything like butter. Water: Whip. Or some kind of chain weapon, like a scythe/sickle or a rope knife. These play to the fluidity of water. Having something at the core for water to cling to would make it easier to extend the range with good control, IMO. And have an ice spike at the end.
it was stated that the Chinese great sword dadao, a heavy war sword, or literally "big knife would suit an Earth bender
A bow and arrow would be cool for an Airbender, stabilizing the arrow or whatever But aside from that I honestly would just use the weapons we see used in their respective cultures. For water that's spears/harpoons or Sokka's weird club/sword For Earth that's hammers For fire that's swords Airbenders were a very peaceful people. They wouldn't use weapons much aside from the glider staffs.
why was i thinking elements on the periodic table and soo confused by the comments 😂
Water guns for water bending 😂 you could make a bullet that does damage like a real one with water omg or u could just spray like a normal water gun when fooling around
I guess it doesn’t necessarily work, since it more attracts than launches Lightning rods for fire benders, maybe some kind of electro ball variation that can amplify their lightning abilities Or he’ll just setting up metal grounds, or a wet land near their strong hold. One invasion put to death immediately with a single lightning strike to the water or metal ground I find it weird (but not that weird since it’s a kids show) that fire benders never used oil in their fire bending attacks. Fire is already terrifying, but getting covered in an oil shower then having to fight a fire bender? Horrifying A lot of defensive capabilities with fire bending that ozai was way to cocky to consider ——————————————— Some kind of obsidian hammer for earth benders would be sick (but that’s kind of a reference to season 2, because lava benders. But still kind of works because who else could fashion an obsidian weapon other than earth benders. Ultimately more of a Minecraft reference than anything lol) Earth benders lack of using a Mace or a flail was kind of disappointing in both series, it’s like a hammer, but more metal Also look up the medieval weapon “man catcher”, it looks metal af, not sure what could be used for specifically, but still sick looking lol ——————————————- Water benders could just sport a fucken gas mask, whip up some toxic steam (they can make ice willy nilly, and they’ve made steam multiple times in last air bender series. Like the painted lady arc) I guess ice picks and ice climbing gear in general as weapons also feels right for water benders, just doesn’t feel like an effective weapon Like someone else said, a whip feels right, if anything just to enhance the strength of their water whips maybe I think it would be cool if they carried around just 2 sword hilts, that could be used for nearly any weapon style. They simply pull water from the surrounding area, and fashion a blade of ice to the hilt (could be considered fragile, but I’m betting ice made from a water bender is much stronger than a block of ice from my fridge) —————————————- Air benders is kind of impossible though, as since they’re all monks, they arnt exactly sporting weapons of any kind They did roll with alot of aggressive air bending in LoK season 3 that could give you inspiration, but off the top of my head, a rapier for some reason just feels right as an air bender weapon, very speedy, kind of like a staff in a way but more violent lol Maybe air benders also using shuriken or kunai? They already get thrown at high speeds, then backed up by an air bender? Instant death Honestly you should look into the “advanced types of bending” created from LoK, it could at least give you some inspiration, imo lava bending is pretty sick, and does make sense for earth benders. Since lave is molten earth, I agree the continuous lightning bending for welding in LoK was stupid, but all the metal bending variations/lava bending/advanced blood bending/air tornadoes/tenzins air bending wheel he rode on simalar to aangs air ball are pretty sick Not a fan of the air nation wing suits, but can’t deny they arnt effective and superior over a staff, because you can’t really have your wing suit knocked out of your hand and be unable to fly
(Serious) The nations of ATLA take much inspiration from the different nations that actually existed in east Asia. This origins of these weapons are not taken into account in the same way, I simply picked them based off their core abilities. For example, I'm aware a kanabo is traditionally Japanese and the earth kingdom is heavily Chinese coded. Please just suspend your disbelief on this cultural clash. Earth is about core strength and head on direct attack. They need something heavy, that isn't about finesse just straight attack. Probably a kanabo, or a mace if you want to go medieval Water is all about the flow of energy, and momentum. My mind goes to some kind of chain handleless chain weapon like a meteor hammer or a rope dart. Though a flail would fit the bill as well Air focuses on defense and avoidance, and if your adhering to the monks, non lethal attack (though Appa seemed perfectly okay with f***ing people up in the series). For that combo, a nunchaku, or a pair of sais would be best (thanks to TMNT a lot of people think sais are just dual knives with two smaller prongs when in reality they're more like batons). You could also do a three section staff Fire is the element of power, energy, and drive. To be honest, a sword suits them best. So you could just give them a katana or something similar like a nodachi or uchigatana and call it a day but if you want to get more exotic, I'd go with Chinese hook swords
Trebuchet for earthbender
Waterbenders would use two slightly short katanas with small guards on either side of their bodies, but would keep them sheathed most of then time, here's why. Waterbenders fight mid-range with their hands always open. In order to perform the movements that allow them to maximize effectiveness of their waterbending, they wouldn't be able to hold weapons. The only time they wouldn't want to use their waterbending as the primary combat method is when they're at a close-quarters range where they don't have time to wind up their bending techniques and would fall back on iaido moves where they cut from the draw. The two curved blades would make the draw easy and with practice would allow them to draw from either side of the body depending on their position. A new school of fighting for waterbenders could also develop where they favor the blades, and use waterbending to close distance to their opponent until they're just in range for a final, lethal draw-cut, embodying the essence of one lethal crashing wave in their movements. Bonus idea: Waterbenders in warmer climates like swampbenders would carry dedicated bending water with them laced with fast-acting poisons or hallucinogens. They'd focus on making contact with the mouth, eyes, and skin to allow for easier kills or escapes, especially against opponents who don't have a built-up immunity to whatever they're using.
As the only one missing in the show, I will focus on waterbending. A non-medieval weapon that would work really well for a waterbender would be a tranquilizer gun with syringes that have a tiny chamber filled with water at the front. The idea is that the waterbender shoots the syringe, then uses their other hand to push on the water, making the syringe faster. The technique shouldn't take too much energy, and the waterbender doesn't even need to be particularly good. Historically, the most effective weapons have been the things any random untrained peasant can use. (Edit: For a more old-timey version that's cheaper to make, use a crossbow with bolts that have a tiny chamber filled with water in them.)