AB Sword Number 10. Square is currently used by Leo. At the beginning of Main Episode-0 during the battle of Void he lends it to Anne so that she could finish off the Queen D-38, after he breaks his right arm in his battle with Blue Ring.
The tip of the blade is a square chisel point, similar to Number 680. Armored Blade. It has the roman numeral X in six locations, four on the blade and two on the handle.