In the context of this conversation, I have noticed that a very important distinction between gun types: guns to carry and guns to learn to shoot with.
I have noticed that many shooting instructors tend to focus upon caliber, especially with new shooters. I still see it with NRA Basic Pistol instructors. They always seem to say "that's too powerful for X". In my experience, it's all about expectations. If the new shooter has been "primed" with the notion that a 44 Magnum is too powerful, then that person will believe that--probably for a very long time. One of the skinnest, small boned women I have ever seen absolutely loved her 44 Magnum "Dirty Harry" gun. It was her hunting and self-defense gun and she shot it very well. However, she never "knew" that it was "too much gun" for her.
Others will state that revolvers are better to start with because of Y. Usually, they claim revolvers are "easier to use", "everyone understands them", and "semi-automatics are too complicated". In my experience, this has not been the case. Most people can understand and remember the functions of the trigger, safety, slide release, and magazine release. It's really not that hard.
One good way to start a new shooter off is to start with a handgun chambered in 22 LR and work them up through calibers using light reloads. If you ask "Would you like to try something a bit more powerful?" The results are very interesting due to human psychology. In my experience, most shooters merrily move up from 22 LR to 45 ACP in a two hour session. It just takes exposure and patience on the part of the instructor.
Of course, being a testosterone filled idiot when I first started, I HAD to have a "good 45". So, I loaded up that first round, clenched my teeth, and shot it. I thought I was going to land on my butt, but no such thing happened. I went on to firing 5 round groups as soon as I realized the recoil was not like in the movies.
Most beginning shooters don't receive the wisdom of our betters and just buy a BFG (big friggin' gun). Then they're told by an "expert" that it is too powerful for them. No wonder they flinch
What does all that have to do with guns for carry and guns for learning?
There are certain attributes that make guns good for carry and bad for learning. A short sight radius combined with an abbreviated grip can make learning to shoot a very difficult task. The reason is that the new shooter has not yet figured out how to evenly grip the handgun, much less focus on the front sight and pull the trigger properly. People learn best when they focus on one aspect of a skill. Thinking about grip, front sight, trigger pull and breathing at the same time is too much for a new shooter to handle.
If your wife is just learning to shoot (and it sounds like that is the case), then a little carry gun like the Glock 26 is not a good choice. The abbreviated grip does not provide enough support for a shooter in learning mode. Even after 10,000+ rounds through my Glocks, I still would throw a round off target every once in awhile.
It would be best if the handgun you choose has an external safety. An external safety is very important; it makes the shooter THINK about whether or not the gun can fire (the rule about never depending upon the safeties notwithstanding). It gives a small measure of protection against negligent discharges, but gun safety is really in the mind of the handler.
I recommend that she look at the Glock 19 and similar sized handguns. They conceal very well for strong-side carry. These guns are also large enough that they may be used for learning. Though many of the new polymer based handguns lack external safeties (including the G19 whose "trigger safety" doesn't count), most are very well built and safe to carry so long as the trigger is covered.
Also, many 1911 style handguns come in 9mm and 40 AUTO. The 1911 has the advantage of two external safeties and a consistent and light trigger pull. The Browning Hi-Power is also available, but has only a thumb safety. And, yes, it's perfectly safe to carry a 1911 or Browning in Condition One (round chambered, hammer cocked, safety engaged). Remember, the gun will be in its holster, which covers the trigger. I never shot myself with a Browning or 1911 over the years
If you work her up to the larger calibers, she will do fine. Though she has tiny hands, she should be able to handle a Browning or 1911 with slim grips if she can handle a Glock. The neat thing about the 1911 is that you can get a very short trigger. The Sigs also have a short trigger option.
Some guns to look at:
Glock 19
Kahr K-9 (should be great for little hands -- just replace the sights)
Springfield Armory XD
Kimber Ultra Carry (or similar like the Springfield Micro-Compact in 9mm)
Sig Sauer P225 with short trigger and a trigger job from Langdon Tactical (langdontactical.com)
Ruger SP101 (loaded with hot 38s or 110 grain 357)
Sig Sauer P239 (trigger job a must)
STI LT in 9mm (if the short grips allow her to fully hold the gun)
Walther PPK
Sig Sauer P232
HK P7M8
.. and so on....
She could also try a full sized 1911. The Springfield Mil-Spec (or GI World War II) has a short trigger and is low priced. You should modify the sigthts, but it's reliable. I've been seeing alot of ladies shooting full sized 1911 pistols lately. You may be surprised at what she'll like!