George,
If she wants it due to arthritis (or any strain related reason) I would strongly recommend finding a cheap electric. Even with a good sharp knife, if your doing a lot of slicing the difference with electric will definitely be noticeable by the time your done- just less pushing down with your wrist. Plus easy to get thin slices. The ONLY drawback imo is cleaning the blades and storing it. I can clean/dry my good knifes in about 25 seconds under running water with some dish soap. The electric's blades are a bit harder and they have some really sticky grease where they attach too.
There was a big discussion once (maybe on ray basso's bbq forum though) about which electric's worked best. Everyone recommended an old model no longer sold, both for ease and durability. People said if you find it used at a garage sale it was still worth it because it was better than any others they tried. I think it had a fish logo on it. I can't remember, but I remember it was the kind my parents had. I'll search and see if I can find it. FWIW- it's not the type I have and mine still works fine after 8 years.
All that said, I drool over the knife Bryan has above. I would like a big granton edged slicer, just can't make myself cough up the money for a good one yet.