あんこくの剣
The Shadow Sword (
あんこくの剣
lit. Darkness Sword) is a cursed Sword that appears exclusively in Fire Emblem Gaiden and Fire Emblem: Thracia 776. In the latter game, this sword is passed into Mareeta's hands by Raydrik, where the corrupted sword essentially takes control of her mind, compelling her to attack anyone at sight, be they friend or foe. The curse is later purged by Saias, whereupon the now-neutralised blade is returned to Mareeta, functioning as a unique weapon that is bound exclusively to her. 
shadow sword (fire emblem)