I have no idea why -- I have tried on multiple difficulty levels, used different save games, but when I enter the room in the tower in Loc Muinne to get the Vran sword, the Guard then pops up.

From all the searches I've found, it sounds like this guy should be an epic battle, followed by the room unlocking. Instead, he goes down in one hit, two wraiths spawn, they die and I'm stuck with the exit closed off by flames and the front door locked. Help?