Specifically: Find the Gauldur Amulet Fragment in Geirmund’s Hall

After picking up the key from Geirmund's skeleton and opening the door behind him, I climb the first stairs (before the drawbridges) and immediately encounter a Dreadlord (I think that's what he is) who during the fight disarms me. I defeated him handily, but then couldn't find my weapons. They weren't on him, they weren't on the ground, they weren't in my inventory .... they simply disappeared. I had to reload an earlier version to try again ... same result. I thought I could try barehanding him --- not possible, and I even tried werewolf form. There are daedric weapons, so I don't want to sacrifice them for one quest.

What am I missing here?

They're on the floor somewhere.

I don't have a problem with this since I'm Heavy armor and can just pummel people with my fists.