Is this device mentioned in any quests or other content? I've just been able to upgrade my Relic weapon using it with the Thavnairian Mist, but I only found out that was what I needed to do by searching online. If I'd poked around where Gerolt was standing, I might have found it. But I could've spent hours not finding it, and if I spent all my time in game poking around at every turn it could be a decade before I caught up with all the content that's been released until now.
I'd rather not skip things, though, so if I've missed something it'd be great to know.