Black Blades are swords of pure carbon extracted from the human body, hardened and made in such a way that they are as strong and hard as steel, yet possess the special qualities of Carbonadium.
Black Blades are powerful weapons created from human carbon fibers. These weapons possess a tough crystal lattice arranged in such a way that it would not break or shatter upon impact, unlike coal or graphite.
The Blades possess strange and powerful capabilities that set it apart from normal swords. It is three times lighter than steel, and is just as powerful. However, the unique feature of the blade is that like many Blood & Bone it uses Synchronization connecting the latent ki within the blade with user's own and gives the user the ability to enhance the weapon with ki without having to use much energy.