Well, I would say to get one box of something in about the power range you're thinking of and try that out. And it's worth more than just a cylinder full, because it may be a matter of working on her technique to the point that the hotter rounds are managable, and it's worth the price of one box of ammo to see if she can handle some better defensive loads. If the hot ammo is too much trouble, then she is definitely better off with lighter loads she can control than hotter one's she can't, of course.
Also, you could have her try something more like an isoceles grip, which has both arms pushing forward rather than the push/pull tension of the Weaver. The lack of fingers pulling on the support hand wouldn't matter as much there. If you are curious about this, check out Ayoob's StressFire pistol book for a thoroughly good explanation of the grip and stance for this type of hold.