Snakes are very dangerous, I have had series of encounters with them. I feel for your friend, he is lucky he survived, obviously the snake isn't that venomous. You were too scared, I believe even if you had stayed the snake wouldn't have done anything to you. Biting their enemies drains them too
You are right friend, snakes usually get weaker after attacking a victim. I wasn't even thinking about this at that moment when I ran, lol.