A poem from the DMC4 art book.
"A shadow knight rose up, holding an enchanted sword named after me. That blade will challenge the devil's reign. Destroying the minions of darkness that stand in his path, the knight finally faced the strongest demon. But his strength was no match for the devils dark wrath. He was defeated and fell into oblivion. The people offered up their prayers, believing in the day when the darkness would pass, and sang songs of remembrance to the fallen knight. These prayers became our strength, our miracle, and by this miracle the shadow knight was reborn, and once again faught the devils power. As the shadow knight said, the darkness has cleared."
This also proves that he was killed in battle. The Knight that was reborn is Dante or Nero I'm not sure. The story is being told by the SPARDA sword.