I bought an Unarmed Brawler NPC, but I don't know how to brawl with him and get XP. I already fought him by talking to him, and that just got us hurt. How do you get XP off brawlers?
You must continue brawling with him (which is what you accomplished by talking to him) until one of you reaches 1 HP. At this point, the brawler will either state that he bested you or that he was no match for you. The loser gets 1 XP, the winner gets a random amount between 1 and 5 XP.
After each match, the brawler's HP will automatically regen to 100% and you may brawl him again (for a total of 4 matches per 24 hours - if I recall correctly). However, you only regain HP at the normal regen-rate.