Main Article: Demon Butterfly Knife
This page is for the appearances of Eternal Feather's weapon form, the Demon Butterfly Knife. Fist shown in the hands of evil, the Demon Butterfly knife is one of the most unique weapons in Soul Eater as it has no meisters nor is ever seen in a full-bodied form. But is based on a obscure weapon never seen with any other weapon character. Eternal Feather uses her weapon to fight based on her personal principles.