Deicide

Deicide is a skill introduced in Fire Emblem Echoes: Shadows of Valentia.

Overview
Deicide enables its owner to kill God-type units; namely Duma, who otherwise stops taking damage below a certain point. It is granted by the Falchion. It is also a hidden property of Nosferatu, Illusory Marth's Falchion and Illusory Roy's Binding Blade.