I was messing around with Froststone ornaments and I ended up claiming the ornament while it was still socketed in my weapon. The ornament slot now shows as empty but retains the appearance of the ornament. I cannot remove anything from the ornament slot and I cannot put any new ornament into the ornament slot.
I'll have to pass this to the code team. It's possible your weapon is bugged permanently, even when they make a fix :/
I mean, it's a little bit funny that I'm a Berserker with a H2H ornament (Katar) that's using the 2HB animation.
I just finished fixing this internally to prevent it from happening after it goes live. Unfortunately if you've got a stuck item with a ghost ornament, you'll need to use an ornament stripping tool to fix it.
There are multiple merchants, including ones available on early progression servers, that sell these. An example is: Plane of Knowledge Darius Gandril @ 55, 1529, -124, Western trader building