Somehow Kvenel the Tongue is able to respawn. I killed him during my first visit to Volunruud. A radiant treasure hunter quest sent me there a second time and he was in the throne room again. The only difference this time is that he wasn't carrying Eduj and Okin; it was a steel mace and iron war axe instead.
It looks like the location is set up so that there are two bosses: Kvenel (0007491C) and a draugr warlock (0004D650). My guess would be that this was done so the dungeon can still be picked for radiant quests. It makes zero sense that Kvenel would be there on a second visit since he's unique. Strangely, he uses a respawning draugr template, but the quest should have disabled him after the first time the dungeon was cleared. The console indicates dunVolunruudQST is not running and that REF 'Kvenel" is NONE, so this doesn't make any sense at all.
According to the treasure hunter's note, the weapon is being guarded by a draugr scourge (presumably the draugr warlock marked as a boss in the location record). [
screenshot]
If you need to look at a game save to reproduce this, I have one right outside of the dungeon available.
Issue Data
Issue #35132: Kvenel the Tongue can respawn in Volunruud