Meh, I think that's just too overly complicated. I like Dono's talent a bit more than that, and I still think that's a bit more complicated than it needs to be, though it does put the action in the player's hands. That is one thing I do like about it.
However, my solution is simple, and still puts the decision in the player's hand, if not the rolling itself. They still get to spend that Despair that my enemies roll when they attacked them. If they want to deflect the shot, that's an option. But, if they'd rather him drop his weapon or run out of ammo instead, they could do that. It is just a simple and effective option that I'm probably going to opt to use, over a more complicated solution like the one that you propose.