Hanzo Sword is a one-hand sword with a chance to wound the target for 75 damage. It is a world drop. This sword used to have the reputation of being the fastest one-handed sword in the game, with 1.5 speed that is faster than most daggers. But in TBC several swords have 1.4 in attack speed.
This item is a reference to Hattori Hanzo, a legendary Ninja of the Iga clan who lived in Japan during the 16th century's Sengoku period. Characters based on him are rife in both Western and Eastern popular culture, including a master swordsmith in the films Kill Bill: Volume 1 and Kill Bill: Volume 2.
Although frequently referenced in popular culture as a saboteur, or Ninja as the claim is made, Hanzo was actually a tactical genius and known for his tireless defense of the Emperor. The blade in World of Warcraft is a Katana that was modeled after the blade The Bride uses in the Kill Bill series of movies - which was a faithful reproduction of the genuine Katana used by Hattori Hanzo in his life.