Dual broadswords

Dual Dao Swords or Broadswords are a type of metal weapon commonly used by Zuko. It can also be used as a single-edge sword. Broadswords have been seen in the Earth Kingdom and the Fire Nation.

Characteristics
Dao Swords are moderately curved and single-edged, though often with few inches of the back edge sharpened as well; the moderate curve allows them to be reasonably effective in the thrust. Hilts are canted, curving in the opposite direction as the blade which improves handling in some forms of cuts and thrusts. Cord is usually wrapped over the wood of the handle. Hilts may also be pierced like those of jian (straight-bladed sword) for the addition of lanyards.

Use
These swords are first seen and used when Prince Zuko hides behind the mask of the Blue Spirit in the episode "The Blue Spirit". He used the weapon to defend Aang and rescue him from Pohuai Stronghold, a Fire Nation fortress in the Western Earth Kingdom. He also used them to threaten Aang in order to trick Zhao into letting them escape. Zuko uses the Dual Dao Swords to conceal his firebending.

Zuko returned under the Blue Spirit guise and utilized his swords in the episode Lake Laogai. In Zuko Alone, he used his swords to fight Gow and his gang. He also taught Lee some techniques with this weapon, saying, "...two halves of a single weapon. Don't think of them as separate, because they're not. They're just two different parts of the same whole." In this episode with the Avatar Extras bonus commentary, it is stated that Zuko's dual swords are meant to represent the conflicting "good" and "bad" sides of him, and that are both different parts of himself.

In Ba Sing Se, Zuko used the swords against Jet at the Duel in the Tea Shop. He had to use them in order to hide in the Earth Kingdom as a refugee, concealing his Firebending ability. In "The Day of Black Sun, Part 2: The Eclipse", when Zuko confronted his father, Fire Lord Ozai, he wielded his swords as a method of defense, since at that time he could not use Firebending due to the solar eclipse.

In the Earth Kingdom, the Dual Dao Swords were seen in "The Swamp" when a man approached Iroh and asked him to sing for a gold coin, using the swords to make Iroh dance instead. At the end of this episode, Zuko, in his Blue Spirit guise, knocks down this man in an alleyway and steals his swords.



Connection
The earliest dao date from the Shang Dynasty in China's Bronze Age, and are known as zhibei dao (直背刀) - straight backed knives. As the name implies, these were straight-bladed or slightly curved weapons with a single edge. Originally bronze, these would be made of iron or steel by the time of the late Warring States. Originally less common as a military weapon than the jian - the straight, double-edged blade of China - the dao became popular with cavalry during the Han dynasty due to its sturdiness and superiority as a chopping weapon. Soon after dao began to be issued to infantry, beginning the replacement of the jian as a standard-issue weapon.