Playing ver 64. I'm on the Black Darts gang quest at the beginning of Tribunal in Mournhold. I have finished the quest, killed the gang, talked to Narisa and she gives me Variners Ring but it didn't show in inventory. I added it with the form ID 102BB5E and it still doesn't show in inventory.
Edit. The ring showed up, I don't know when but it seems to be a ring related problem for me. It just happened with Barilzar's Mazed Band which I looted off Barilzar's dead body. I know I'm supposed to have it because i got the updated journal entry but It's not there. I haven't tried to complete the quest yet, I'm going to finish other quests first. If this ring suddenly shows up in Inv, I'll let you know.

Variner's Ring [0102BB5E] is
Variner's Ring [0102BB5E] is adding successfully into my inventory and equippable. I am running v064 with Morroblivion-Fixes v1.8b. I would try starting a new game and then testing adding the ring to your inventory, just to verify whether it is your Morroblivion installation or that specific saved game which is broken.
If you are still experiencing the problem after starting a new game, then post your load order. If it works in a new game, but not in your saved game then your saved game is probably corrupt. Fixing it may be possible, but will require custom patches, using a save-game editor and/or hex editor.