It sounds like your friend was special forces, perhaps? If so, he has the skills ... and has been trained for the 'no-conscience' kill. I'm glad you talked with him - it musta freaked you out, though!
It's true that the immense violence that the WT encourages to be perpetrated upon children, has damaged many of us. Like you, I dealth with the belt (or wooden spoon, or fishing rod/switch), but being fist-punched like your friend, has a much more 'personal' effect on the child - fist-to-flesh is much more personal than belt-to-flesh imho, though I'm not minimizing anyone's pain through beatings as a child. Add that to 'shoot-to-kill' training, along with the fact that he's contact his parents once a month for 20+ years ... sounds like a ticking time bomb. I hope he finds peace, and bouquets to you, for being there for him. xoxo
tal