Sulmus has been seen riding through the Fallows, and it is believed that his saddle will be a valuable part of a collection of bounties.
'Hail, ${PLAYER}! I hear you are quite the foe-hunter in these parts. Perhaps we can work together, eh?
'I am a collector of odds and ends -- trophies of the enemy. I believe that someday they will be of great historical value, you see.
'A Warg-rider named Sulmus, a vicious hunter, has evidently been seen riding around the Fallows of late, slaughtering beasts and men wherever he goes. Will you bring me his saddle? I'll see that you are amply rewarded.'
Sulmus can be found in the Fallows by taking the road directly south, and then searching for eaten prey south of the first split in the road.
You should summon and defeat Sulmus, and collect his saddle.
Britric is in Forlaw.
You have collected the saddle of Sulmus, and should now return to Forlaw to collect your bounty.