Over in this thread, it was mentioned that we have this WoB from an inscription: "Preservation was the first shard to be held by someone outside the original 16."
Assuming this refers to the events in Mistborn era 1, do we think it is possible that any of the Shard holders initially picked up one Shard but then traded with one of the other Vessels for another? If so, any speculation on who might have traded and why?