I'm curious about these, are they used to make anything really good? 
 
I ask because the thing that you can trade items for souls would normally do 100 souls for armor... but these were 1000 a piece. I held off on selling them because it seemed a bit fishy. So is there something awesome you can do with them? 

I was wondering this myself, just unlocked that dude, and wondering if I should sell these.

No idea, but I would hold onto them. The game seems to like making the least significant loot important later on.