and having control over the selection of a weapon.
The only person who actually has "control over the selection of a weapon" is the person that is going to be carrying it.
The simple fact of the matter is that unless the handgun properly fits her and she likes it she'll carry it or not regardless of what some stranger, friend or spouse thinks she should carry. Pretending otherwise will lead to enormous disappointment (or an eyeopening educational opportunity).
Find out what fits her and then get that. To do this she'll need to be the one to pick it. The best thing that you can do is facilitate the selection by finding out where the greatest selection that she can try out can be found, doing what is needed to make it easy to get to and then paying for what she tells you fit her best that she liked.