Part 57563 is a BIONICLE blade part that was introduced in the theme in 2007. It was most commonly used as knives though sometimes also as fingers. It is called "Weapon 1 2007". It also appears in themes like Hero Factory and Power Miners, as a drill in the latter case.
![[1]](https://static.wikia.nocookie.net/lego/images/4/4f/Peeron_logo.png/revision/latest?cb=20110104203046){kind=logo}