Howdy! The etc item Soul Contract dropped by Thanatos drops without the quest for it active. I believe it's used to unlock the Dark Knight skill Aura of the Beholder. Library names Contract of the Spirit as the quest name if that helps.
Sort of related to this, almost all (if not all) quest exclusive items keep dropping even though all have been collected. In GMS, the quest items would stop dropping after having collected all of it.
