Henry the Bruiser

Work through the bare-knuckle brawling questline and beat the region's top fighter at the end of it. Bump your Strength/Warfare and unarmed combat first - it's a proper fist-fight, no weapons - and it helps to learn to master-strike (perfect block into a counter) with your fists. Save before the final bout and retry until you win. Follow the brawler quest chain through to the champion.