"Oh a Ancient Nord Puzzle Door...how quaint! Normally you can’t open these without a key, but there’s a trick to it, actually…"

*picks the lock that would normally be completely unopenable without an Ivory Claw-like item*

Also his battle quotes are so tough! What a don!

Isn't he using the skeleton key?

Was he? I didn't think those doors had a 'lock' to even use the key on, I assumed he just was tinkering around with the gears/hinges.

Yeah, that's my suspicion as well... although I don't think it actually works for the player... *shrugs* Maybe something to test, perhaps. On another front, I did try to Dead Thrall Mercer, but he wouldn't follow me out of the dungeon for some reason.