I just beat Lord Volmyr, I've been walking around with the Light of Dawn on my back, but I haven't gotten any quest updates after his death. (This quest is not acknowledging that I killed him)

UPDATE
Nevermind. I solved the problem.
I put the sword into Lord Volymr's inventory, exited inventory, then went back and took the sword from him. The quest update window appeared before exiting the inventory window.

First, I had tried dropping the sword on the ground, and then picking it up, but this made the game crash....

If anyone finds themselves in a similar situation, I think it's COBL that allows you to move quest items.

I don't think that's Cobl instead I think it's more likely the UOP who has that feature.