Apparently that's common for compact rimfire revolvers.
(May or may not be the gun in question, but it fits the description.)
If you lighten the hammer spring then the trigger pull will get much lighter but the gun might not fire when the hammer drops. That is unacceptable in a protection piece. You can lighten a spring in the trigger for a partial reduction; you still have to pull the hammer's weight but the trigger's extra can be cut down.
The article doesn't go in to the effects of lightening the trigger spring; I suspect that this makes it less improbable for trigger inertia to cause a ND. If the hammer is down then the weight of the hammer, being sufficient to cause the operator trouble, should prevent this, but if the hammer was already cocked and the gun were subjected to sudden and considerable acceleration in the direction of the muzzle, perhaps by being dropped on its back, I'm concerned that it might go off.
I recommend re-evaluating the choice of weapon. If you do, take a closer look before buying.
According to "poodleshooter", reducing the trigger spring can also slow the trigger's reset, delaying the ability to take the next shot. Which makes sense, but even slowed the gun may be faster than she is.