Know Of Any Tradeable Quest Items You Can Only Get One Of?

I know of one, the depressing items. They are needed in the quest of Bob's lost soul. You can only get one Depressing Spear/Bow/Shears/stick per character.

Know any more?

Thank you!

 

This is not true, depressing items are just normal items dropped from some mobs around lvl 40 and lvl 1-10.
However, Bobs Mythic Items are tradeable and only obtainable once per class, I'd have to think more about any others