I too killed him in the Blackpits and while my quest log didn't state that I needed to find him (in fact, a spirit I talked to in the barracks told me Reimond wasn't in Arx), I found his spirit in his lair!! And I thought I consumed it, because I reaaaally didn't like Reimond. But his spirit was there, talking to me (with no audible voice) like I never killed him in the Blackpits and then vanishing before I could consume him...
I remember the fight in the Blackpits, I teleported one of the Black Ring near the ship (after I reloaded and noticed they get shackled, I wanted some witnesses) and noticed Reimond was kinda fleeing, but I thought he was just trying to kill my Black Ring friend, so I kept teleporting him back. Now I know he was kida supposed to escape death there lol
