My late paternal grandfather, who I met for the first time in my early twenties, (long story), was a professional boxer and was an "old man" when I first met him. One of the first times I went to visit him at his job as a doorman for a nightclub in Greenwich Village, his face was badly bruised and I found out when I went to the hospital that he had an orbital fracture.
I asked the manager of the club what had happened and he told me that he had knocked out three of four mugs that had started a ruckus and attempted rob the place. One landed a good shot before fleeing.
The biggest problem I have with the aging process isn't that my strength (in most regards) isn't as much as it was in my thirties, it's that the cardio will never be the same...therefore I try to avoid a situation where I might have to grapple for any kind of extended period. If it comes to it, for me it would be "strike and move" and un-holster the weapon if need be. (Given the choice...which is a big "if".)
Interesting topic. Each of us will have varying skill sets in this arena.