My son is a brown belt in karate (and would be a black belt but he stopped going right before his test).

I have been trained in two armies and, yes, have been in life and death situations -- including combat.

My son would probably stand up to a man with a knife, but not one with a gun.

Today, at age 63, I very much doubt that I would have the courage (or strength) to go after a young man with even a small knife.