I was a 54 pally collecting Snow griffon eggs for Coldain Shawl Quest. While i was in Combat the Dervishes agroed me, I found this to be a common drop from them. I was mostly camped beween the Orc fort and the sleeper. They fall of any type of Dervish.
I looted one of these off a Dervish my first night in Velious. The freaky thing was that my partner told me I'd get one in a few minutes. It sounds like its a fairly common drop. I also got a cold-based dagger too. I welcome the gems bonus to Int and Mana, but keeping it makes me encumbered. Still, it's a good trinket.
Mine was off a blue Blizzard Dervish. I am a 51st lvl Druid. Best range item I have seen that I wasnt REALLY expensive. Does anyone know what quest it is involved in though, Maybe it will be even better!