My honest opinion is if your wife is shooting a light set up you should be going the other way. I would be looking for a heavier arrow to get better penitration. You would have to drop a fair amount of weight to make a real difference in percieved trajectory.

If she really wants to hunt and you want more speed I would suggest working on getting her to draw more poundage, within reason, we don't want her over bowed. Or look at getting a more effecient bow.

I shoot a fairly light set up as well, like around 50 lbs at 26 inches of draw. I shoot 450 grn arrows when I hunt.

I know that isn't what you wanted to hear, but I think it would work better.

Paul