Restia Ashdoll  

Vorpal Sword, レスティア・アッシュドール

Restia is Kazehaya Kamitos spirit, which takes the shape of a young girl with high-level darkness elemental powers. In her weapon form, she becomes Vorpal Sword - a black demon sword that can penetrate truth. She has the ability to transform into a sword on her own and be wielded by others without requiring a contract.