And maybe buy your wife a hand strengthening device.
This is good advice. If you can get her to squeeze a rubber ball once a day her strength will improve.
I normally change my stock springs on all my revolvers. The J-frame is a bit tricky, as the smaller the revolver the stronger the springs have to be for consistent ignition. In addition, the J-frame mainspring is a little bit harder to remove than the K/N frames' mainsprings.
However, it is not difficult to change out the mainspring, and not too difficult to change the rebound spring (there is a tool that makes it very easy). I would suggest changing the mainspring from 8.5# (standard J-frame) to 8#, and the rebound spring from 14# to 12#.
Then, take it out and shoot 100 rounds of your self defense ammunition
in double action. If you have any light strikes, reinstall the original mainspring. If you have trouble with the trigger reset, replace the 12# rebound spring with a 13# spring (or 14# if necessary). It can get expensive to test, but you need to be confident in the ammunition your wife is carrying.
I would not suggest doing more than that without some serious study on the matter. It is a job for a gunsmith, but there are references available and help videos on the web that can walk you though the simpler stuff. Just be prepared to spend a lot of money fixing it if you screw up.
I have done some work on my own smiths, and have never screwed anything up that wasn't fixable. I have one revolver, a model 625, that will not reliably ignite any ammunition other than ammo with federal primers. Federal primers are the softest around. However, I rarely use it for anything but range work, and, when I use it for home defense, it has federal 185 grain hollow points loaded in them, and I've never had a light strike with them.
On the other end of the spectrum, I have a model 15 that I sometimes carry, but is usually my car gun. I've replaced the springs with wilson combat springs, and did some minor polishing, and it will shoot anything I put in it, even if the trigger isn't as smooth and light as the 625.