While the light weight and hte small grips make it easier to carry it makes it harder to shoot.
A stainless 640 with an over sized rubber grip would be my choice for a lady.
Yes it shoots 357 mag, but you don't have to. 38 specials will work.
The heavier gun reduces recoil, the larger grip spreads out recoil. Makes it easier to get hold of and easier to point/ aim.
and yet it is still small enough to carry.
The more confortable the gun is to shoot the more often she will shoot it and become good with it. The more she shoots the better the mussle memory when needed.
The revolver is simple with a limited manual of arms. If it does not fire, pull the trigger again. If an auto does not go bang you have to do a few things quickly. Your idea of a revolver is right on as a first gun. If she likes shooting and wants to get involved with IDPA or steel challange then a new gun cna be purchased.
5 rounds should be enough to make hits and run away.
Yes, it is not a girly product, but you can paint the gun Pink.
For while I had a pair of S&W M65's with the 3" barrels, one was a lady smith and the only difference between the two was the pinkish case, the rose wood grips, and the words lady smith on the barrel, I stripped all that off and added pachmyer grips to both as house guns. One upatairs and one down. The Lady Smith cost $50 more and hte small wood grip intesified recoil.