Hakai's cannon weapons

Samehada is a large sword of comparable size to the Decapitating Carving Knife. It is described as "the most terrifying of all the Seven Swordsmen's blades".[1] At the tip of Samehada's handle is a small skull. Its actual blade is covered in scales, which causes it to inflict shredding or shaving damage rather than cutting what it comes into contact with. The effect is similar to a shark's skin, hence its name. While it ordinarily remains rigid, Samehada is able to stretch and bend to a great extent, allowing it to be used like a flail.
Samehada is unique for being a sentient weapon that gains nourishment from the chakra of others. It is happiest when engorged with chakra. Although it constantly feeds off of the chakra of its owner to survive, but only a minimal amount. Its largest "meals" come from fights wherein it absorbs the chakra of its owner's opponents. Such an ability allows Samehada to literally slice through an opponent's jutsu and even prevent jutsu from being performed by absorbing all of the opponent's chakra. This is particularly useful when fighting jinchūriki, as Samehada can quickly deplete their large chakra supplies as well as remove their chakra cloaks. Samehada grows larger from the chakra it absorbs, its scales becoming longer and its mouth, located at the tip of the blade, becoming more pronounced. Keeping Samehada wrapped in bandages apparently inhibits this growth.
While the ability to absorb chakra is useful in defeating opponents, it is also beneficial to its user. Samehada has the ability to transfer the chakra it has absorbed to the wielder by partially fusing with its wielder, so it can be used to either heal the wielder's injuries or replenish their chakra reserves. This makes the wielder of this sword extremely difficult to defeat. It is drawn to others with large chakra supplies, allowing it to be used as a sort of sensor. A wielder of this sword, such as Kisame Hoshigaki can take this fusion one step further by completely merging with Samehada. Doing so causes him to become much more shark-like in appearance, growing fins and webbed hands that allow him to move through the water with greater ease. Kisame receives some of Samehada's abilities while in this form, such as being able to extend spikes form his body for attack, and absorbing chakra when others come into contact with him, as well as the ability to track chakra.
As a sentient weapon, Samehada chooses its user. If someone it disapproves of tries to wield it, spikes protrude from the handle, forcing them to release it, and Samehada returns to its chosen owner. After Kisame killed its first known wielder, it came into his possession. The user can summon Samehada into his hand with ease. As well and cause to fly to him if across the battle ground. The user and the swords chakra became identical, so the user can stay hidden in the sword if it choses.