There is a Merchant in Duskbarrow, south of the entrance to the village, that is continually harassed by a former mercenary that thinks all of the stuff he’s getting from nearby ruins is worth a lot of money. You will need to journey to those ruins, so make sure to bring along either H’aanit or Olberic with you, as one of them will be required. Exit Duskbarrow and when you find the save point not far from the village, head east to find the entrance to Moldering Ruins. The NPC you need is found not too far from the entrance and you will need to either Provoke or Challenge him. With a strength of seven, he isn’t too challenging, resorting to physical attacks the majority of the time, although he can buff his physical attack. Once you beat him, the quest will end.