...but for what exactly? I've played Morrowind before and can't find anything to do with this ' threat' she talks about.
The only thing I can link is that in Morrowind she doesn't allow men into Tel Mora - I'm guessing because Xykenaz said that one day he'll appear before her as a mortal man to pull her into Coldharbour.
Unless, the threat she refers to is the true Nereverine?