How exactly do you beat this thing? I've read every tutorial on the web and they say to have such and such weapons, and to attack it when it's down, kill undead, and repeat the process, yet I've been playing this with my girl friend and we've hit the crap outta that thing even imported our characters and went through the game again with best weapons and armour for the time and still can't seem to find an end to this boss.

Are we missing something?