Six. I just found a simple way to defeat Improved Faldorn.
Weimer has modded (i.e. cheesed) Cernd to have a decent chance of beating her. For some reason he has several thousand hitpoints and they fight for several minutes before a winner is decided.
Well good
The downside is the party doesn't get the experience, because Cernd isn't in the party and is fighting the dual on his own. If you try and get Cernd to fight her legitimately... God help you.