A Sig 226 too heavy?
For any grown adult, male or female, unless they are unusually weak... I find that complaints about the weight of the average pistol to be more psychological, than an actuality. Same with manipulation of the firearm, like racking the slide, and even recoil control. (there are exceptions to this of course) Most new shooters tend to not be as aggressive as they need and should be, when using a firearm. Not gripping tight enough, letting muscles relax too much... Things like that.
Meaning... Almost all issues are actually down to technique, rather than physical inability/limitations. With much of that stemming from mental reasons and/or inexperience.
Also... Why will she not be active in the decision?
That may be a clue that she really isn't into the whole shooting thing, or that it is just a passing curiosity... An effort to spend time doing something you like. (not sure the relation she is to you, so you need to judge her enthusiasm for yourself)
But it could be that she is a bit intimidated, and hopes to avoid feeling like a bad choice was her fault.
An idea, would be to make a short list, and let her try them out, and give her thoughts. How the gun feels in her hand is important, and how comfortable she is with the weight.
She does need to understand that lightness means more recoil on average. A small, light and dainty pistol may feel nice while you are holding it at the sales counter... But it will not feel so dainty when you pull the trigger on a live round. So discuss these things before making the choice.
For smaller statured people, with small hands, having a slim comfortable grip goes a long way to making shooting fun.
Key thing, do not go too small. Nothing smaller than a "compact". Think glock 19 sized... There are a few pistols in that range. Its a good size for most smaller shooters as well.
Do not go smaller than that, or lighter, or single stack... As was mentioned... That increases felt recoil and can make shooting less fun.
Bigger and heavier is better, within reason of course.
A S&W M&P is a nice comfortable pistol. Not too heavy either... Using the small or medium back strap, would be the best bet. I find it shoots mildly, and is easy to operate.
I find the HK VP9 using the small backstrap and medium side panels to be very comfortable in my hands. I have smallish hands... well, more stubby fingers... Easy to rack the slide with the rack assist tabs too... So its a good one to put on the short list. (My VP9 is one of my favorite pistols)
The Walther PPQ is also very comfortable. My fiance found it to be a bit slick in the hand under recoil, and was not a fan of it when she was first learning. Now that she has more experience, she doesn't have the same complaint, it is one of her favorite pistols now. (she is trying to claim it as her own)
I find glocks a bit bulky in the hand, the Gen 4 is better than the older versions, but its still not the best feeling pistol to me, but I still manage to shoot it surprisingly well for not really liking it a lot. That has warmed me up to them a bit more. If it feels good in her hands, its not a bad choice.
The new FN 509 or the prior FNS model are nice pistols. My fiance really likes the feel of the 509, saying it felt very nice in the hand. The FNS is a bit aggressive with its grip texture, which turns her off of it, but I personally like the grippy feel of the FNS... But I do agree the 509 feels better.
The new CZ P-10 is very nice in had as well. I can't ay too much about it, as I have only handled it for a small time.
The CZ P-07 is a good option if you want a hammer.
Also... In the end, if she is having issues with the recoil of 9mm... Regular practice with a 22lr is key to helping hone fundamentals, and make practice useful and fun.