Nightmare-Soul Edge

Nightmare Soul Edge is the central antagonist in the Soul series of fighting games and namesake to the first installment. Originally forged by human hands, at first Soul Edge was just an ordinary sword, but after being bathed in blood and hatred countless times, the sword turned into a demonic weapon and gained a wicked soul called Inferno. Those who grasp its hilt are unable to escape its curse, as its spirit invades the mind like a parasite and drives its wielder insane. As its blade is soaked in blood it grows in power, yet it manages to shine a polished red. Soul Edge is distinguished by the animate eye.

Soul Edge's curse is called malfestation, and is inflicted upon those who wield not only the sword itself, but those who come into contact with its shards. Normally, the Evil Seed transforms the person infected into a demonic monster and feeds off the host's inner sinful deeds of bloodlust, controlling and manipulating their actions forcing the user to take the souls of whom they defeat in battle, as it does to Zasalamel when he obtained it, Siegfried-Nightmare, Lizardman, Necrid, and Cervantes de Leon, from the main series, and Geki and Maki from Soulcalibur Legends, as well as other people mentioned in characters' backstories. The curse's newest victims are Amy, Voldo, Raphael, and Sophitia and its newest allies are Tira, Solnhofen and Johan Dürer. Many people have fragments of the cursed sword inside their body, such as Astaroth and Maxi, or others keep a fragment or fragments of it, or in order to test their own powers, such as Mitsurugi or Rock.