Tekketsu

The Tekketsu (鉄血, Blood and Iron) is a katana wielded by the first mate of the White Scarf Pirates, Aisa Himegami. A blade created specially for her during her time in the Cipher Pol, the blade was fed a so far unknown that allows it to soaks up all the blood that falls on it and then convert that blood into iron to change its own shape or create more blades.

Appearance
Tekketsu has the appearance of a traditional, Japanese long-sword with a dark-red colored hilt and sheath, and a light-coloured chape. It has a nearly round cross-guard with four equally spaced indents on its circumference.

Abilities
The blade was fed a Devil Fruit that allows it to absorb blood and use that absorbed blood at any later time to create iron that can be used to make new blades or can be used to change the shape of Tekketsu itself. The blades so crated can be reabsorbed by the sword, so that they can be used again at a later time. As the blade uses blood to create iron, the more the amount of blood that Aisa spills using the blade, the stronger Tekketsu becomes.