I've reached the point in ultima 7 where you need to get the ethereal ring from spektran and it's impossible to kill the sultan's stone harpy. I've read several walkthoughs that say that I should have no problem if I have the blackrock sword (I do) or the ability to become invisible (I do) but the sword refuses to use the death power and I've hit the harpy for three minutes straight with no apparent effect. Not even the armageddon spell seems to effect it at all beyond knocking it down or a bit of damage flickering.

Is there someone I need to talk to or an item I overlooked or is my save file ruined?

I tried uneqipping my sword and I killed it without any trouble at all. Thanks for the help.

Weird that none of the walkthroughs I read mentioned that though...