Its a bug.
Once I was pvping my friend Warrior/Warlock with my Warrior/Cleric, and we were mostly using shield KB and Cleric skills, when either one of us gets his skill interrupted it would leave the casting ring behind it. Once we were done pvping there was like 5 warlock and 6 cleric rings just staying there. Scars of war lol.
Thats a cold wizard spell ring.

Bugroad.