Scissor Blades

The Scissor Blade (断ち斬りバサミ) is a special weapon developed specifically to cut Life Fibers. It was created by Isshin Matoi, and was divided into two half blades (片太刀鋏) in the moment of his murder.

Red Scissor Blade
Ryūko Matoi owns the red half of the Scissor Blade. It can expand into a longer sword (known as Decapitation Mode) or collapse into a normal size scissor half.

Purple Scissor Blade
Nui Harime owns the purple half of the Scissor Blade. Unlike Ryūko's half, it has a circular handle. It is as of yet unknown if it can also change size or form, though it is likely.

This half of the Scissor Blade seems to have changed color at some point, since it is shown to be red during Isshin's murder.