In the home version of Soul Edge, an extra character named "Siegfried!" was added as an unlockable character. "Siegfried!" was an alternate version of the normal Siegfried taken from his no-input ending, where he was consumed by Soul Edge. This early version was very different from the former Nightmare, having crimson-red armor and a more flesh-like design, almost like if he was part of Soul Edge itself. He has no story nor ending, and only used Siegfried's Soul Edge without effects.
- See main session: Nightmare's Weapons
- Siegfried! wields Soul Edge (that has not grown) and in Soul Calibur III it's called Soul Edge (Cocoon).
- Starting from Soul Calibur III, Nightmare is not Siegfried's alter-ego anymore, ending "Siegfried!'s" appearances on the series.
- If "Siegfried!" had remained on the series, Nightmare would have donned the crimson armor and would then be called "The Crimson Knight" rather than the Azure Knight in all the other series.
- Whereas Nightmare's right arm is mutated, Siegfried!'s left arm is mutated. Interestingly, this makes more sense as Nightmare/Siegfried! holds Soul Edge primarily with his left hand.
- An illustration in Siegfried's Edge Master Mode ending depicts Siegfried! wielding Cervantes' Soul Edge swords rather than his own version of the male sword seen in the Arcade mode version of the same ending.