How often and when should you let the angry person or weaker person win?

Never let them win because they will think every fight will be easy.

Well, a person who lets their anger dominate them is clearly weak, because it clouds the mind from functioning properly. One who stays calm, rational, is the strong one. Anger often puts one at a disadvantage, if it's not properly dealt with. No, don't let them win if it gets physical, or verbal, if you can help it. Make them earn it. They'll learn anger, like fear, is not an advantage if it gets past a certain point.

If it's at a verbal level ,  I'll let them take the win if it stops a physical confrontation,   if I can control the situation  verbally I will ,  depends on the feel of the situation.    I work in an environment that can be volatile and my response is normally called in at the higher end of an escalated situation.  

Why would you let them win? Did they earn the victory or win? Is it a game or a fight? Either way it does not matter.

Is it unsportsman like to not let them win? No not at all.

Angry person sometimes need to have rear end kicked a few times. Angry people never need to win. That is why they angry, they never win because they are angry and feel they deserve t win. Well winning is not something that should be given, it should be earned.

Winning and losing are also teaching aides. Without loosing one can not win. And the biggest issue is giving someone the win, THEY NEVER :LEARN. Make them earn it not just give it.

I don't know. You sound too smart to be on this website