Ok, so I just spent about an hour and a half in the south barrows killing everything in sight. I have 17 blackened skulls now but not on Decrepit Wight Skull . Is there like a certain area you need to go to get these, or am I just having bad luck?
Might come from the wights in the swamp south of the road by the stone talker (Arric). I have a few of them and that's where I was doing some hunting. The wights in Hagamar (swamp north of the road) drop Orthodox treasure iirc.
(That would be in the Lone Lands east of Ost Guruth)