After the demon Acathla came forth into this dimension, it was slain by a "virtuous knight", who pierced the demon's heart with a sword. Instead of dying, Acathla turned into stone until he could be awakened again by "someone worthy". Eventually, the knight died, but not before blessing a second sword in case the demon ever awoke again. Buffy used the blessed sword of the knight to defeat Angelus and sent Acathla back to dormancy. This made the knight responsible for both defeats of Acathla, albeit only indirectly on its second defeat.