Okay, you want a weaker pull. To do that you can do a few things, and I'll use Glocks as an example since I have a few different ones and it should make the comparisons easier and clearer. One is to get a lighter spring, but you can't go too low, and you should aim to use lower powered ammo. I use a 15lb. spring in my G17L instead of 17, but I fire a slower target round in it. Keep in mind too that a weak grip can cause problems with some weapons. I hear a weak grip on a Glock can cause malfunctions, but I haven't tried it. I suspect it has to be pretty weak, and I doubt she's that weak.
Another way is to get a pistol that has a heavier slide. Because the 9mm will generate similar recoil energy in any pistol, they are all designed similar in regards to the slide weight/spring weight combination. You can reduce weight in one if you increase the other without changing the load you fire.
A case in point is the G27. It takes a lot of strength to pull that back (comparatively) and my wife can't do it easily, it has a smaller, lighter slide. It also has a shorter spring, and that doesn't help either, as the shorter spring requires more force to collapse per inch than a long one. Even though they require the same amount of force overall, the shorter one will be perceived to be more difficult.
So heavier slides that have longer recoil springs will rack the easiest given a fixed cartridge. Lighter springs can be used with lighter loads, but you have to make sure reliability isn't compromised by the change.
Of all the Glocks I have, the G21 is the easiest by far to rack. I reckon the G20 would be too, but it hasn't been shot yet. Now my wife is recoil sensitive, and she hates the G27, she is okay with the G17 and carries one, but the one she likes shooting the most, ironically, is the G29 10mm with 200gr. XTP's handloaded to about 1000fps (but not 155gr. or 180gr.). She hasn't shot the G21, but I suspect she would like that even better with heavy bullets at lower speeds, say 230gr. at 800-900fps. A non +P load.
So don't rule out heavier calibres, just the opposite. Some ligher calibres can be the devil to cock. While she likely would have difficulty charging the G29, the G21 or G20 may be okay, and in addition to those slides being heavier, they are wider and easier to grasp too. Using a big heavy bullet also changes the recoil profile from brisant to dull --instead of a quick SHOCK! you get a slow shoooove. Go try one. Best advice is to go to the gun store and just try 'em all. I've given you the basics that are governed by physics, so think about slide weight vs. spring weight, think about a full size pistol and not a compact.
I just thought of another option, but it probably isn't best for carry. Race guns sometimes have cocking knobs. They make one for Glocks that swap out with the rear plate. Makes it easier and faster to cycle, but it also makes it easier to get hung up on the draw.
The revolver will certainly eliminate charging difficulty, but make sure she can operate the trigger DA and the hammer SA. My wife's 317 .22 is very heavy, and she can't hit anything because it is so difficult to pull the trigger. The 686+ 6" .357 conversely, is her favorite handgun period. Smooth trigger and hammer, but it has had a lot of work. Low recoil, but it is big. They make a 3" version though, and I bet that would be an ideal carry revolver. Easier to conceal than the 4", but more power than the snub.
Outfitting the wife can be difficult, and they will surprise you at what they like and what they don't like. I never thought 10mm would be appropriate for my wife given her specifications on what a pistol should be (no recoil, weightless, tiny, but sufficient power and accuracy?). But she likes it, and also my friend's daughter, who is 16, prefers shooting that G29 with heavy bullets over the G17 and the G27 too.
