Cat approaches you with a lethal weapon and robs you and someone is going to impose some "fair fight" fantasy on you? You can sure tell that we have a shortage of people who have ever actually been in a serious fight.
I know that the limp-wristed have made this the law of the land (mostly), but if someone has threatened your life and stolen a portion of your livelihood then his is forfeit at the first opportunity. Screw a bunch of fair-fight bullcrap.