[spoiler]I never even saw his dark magic when I fought him. Had to go back and watch a vid on youtube to check. Maybe the canon way to fight in the first game is to kill smough last and when he hits Ornstein with the hammer he steals his lightning abilities. He could have survived and left to follow the princess and her giants across the sea. When he gets there he finds that he no longer is as effective without that ability and needs to find a new strength to help him along. Maybe that is how he has lived so long.[/spoiler]