Yeah she is a foil fencer. The majority of our sparring has been me having to break her from some of those habits. Fencing really does train you to do some very bad things because of the sport nature of it.
Being a foilist myself, I find that foil tends to be the toughest in that regard. All the core mechanics are good - extension of the arm, distance concepts, footwork - but the restrictions due to rules can throw people off. Epee is basically a free for all, so with the exception of cutting it carries over to lightsaber quite well. Saber at least teaches you to cut, which is very useful.
IMO, if you studied all three weapons extensively, you'd have everything you need to be very dangerous with a lightsaber.