Samehada

Samehada is a large unique living sword of comparable size to Zabuza Momochi's Decapitating Carving Knife, and is described by Chōjūrō as "the most terrible of all the Seven Swordsmen's blades."[1]
 * Name: Samehada (鮫肌; Literally meaning "Shark skin")
 * Wielder: Kisame
 * Debute (Manga): Chapter 141
 * Debute (Anime): Episode 81

Unlike a regular sword, Samehada is covered in large scales that shave or shred any surface instead of cutting it, much like a shark's skin - hence the name, and has a small skull at the tip of the handle. It is usually wrapped in bandages. The sword is able to stretch and bend, allowing Kisame to swing it at his targets like a flail. During his fight with Killer Bee, Kisame unraveled the bandages around the blade to reveal Samehada's true form: the scales grew longer and opened outwards, the hilt elongated itself, and the weapon opened a razor-teethed mouth at the end. The more chakra it absorbs, the larger it gets.

Samehada, aside from shaving the opponents, has the ability to quickly consume the chakra around it, allowing Kisame to literally cut through his opponent's chakra, this ability is particularly useful when fighting Jinchūriki as Samehada is a perfect counter against their massive chakra supplies as well as being able to drain their chakra cloaks. This ability can be used even if the sword is still wrapped in bandages. The amount that it can absorb is unclear, but Killer Bee notes that it can absorb no more than six of his chakra tails at a time. It has also been shown to consume the Nine-Tailed Demon Fox's chakra from Naruto Uzumaki's body with no ill effects.

Samehada without bandages.Samehada is also a sentient weapon, that along with being able to sense chakra levels,[2] only allows Kisame to wield it. In the words of Kisame, "It acknowledges only me." When Might Guy attempted to wield Samehada and use it against Kisame, it responded with a flurry of spikes protruding from its handle, thereby injuring Guy's hands, and returned back to Kisame. Being a chakra sensing weapon, Kisame claims that Samehada is attracted to intense chakra, such as Killer Bee's. Samehada is noted to be in a pleasant state while engorged with copious amounts of chakra, and can even move on its own accord to evade attacks.

Kisame and Samehada merged.The chakra it absorbs can heal what are otherwise fatal wounds, which can also be used to give its wielder (Kisame) near limitless stamina. Besides leeching the chakra of his opponents to keep his strength in proportion with their's, Kisame can also fuse with Samehada. The resulting transformation stresses his shark-like appearance, effectively making him a "tailed beast without a tail". In this form, due entirely to Samehada's presence, Kisame can not only sense an opponent's chakra but any direct contact made with his skin will also result in the absorption of the perpetrator's chakra. In order to conduct attacks, Kisame can forcibly extend various spikes from the pectoral fins present on either of his forearms.

This weapon is also highly sought after by Taka member, Suigetsu Hozuki, and is stated to be the sole reason Suigetsu joined Sasuke in his hunt for Itachi Uchiha. Suigetsu believes that he will be able to wield Samehada if he kills Kisame, but it is unknown if this is actually true. Samehada has openly betrayed Kisame in favor of Killer Bee's and the Eight-Tail's larger chakra capacity, so it appears that the sword will simply serve whoever has the chakra it prefers most.