Very few guilds had 1 Atiesh, let alone 2. My guild at the time never even got one - we had Cthun down for the base, we had the 40 splinters for the shaft and all that was missing was the Head from Kel'Thuzad which we never downed because of the cockblock called Four Horsemen. I'm guessing (note - guessing, not fact) that the Atiesh FoS is THE rarest FoS around, maybe even rarer than Old School Ride.
It IS though true that each Atiesh had its own special aura - Can't remember who gave what but they were 2% hit, 2% crit, mana per 5 (this was the druid one, I remember drooling over it on Thottbot) and the last one...escapes me. Also, each Atiesh model was identical - but the piece of rope/feather hanging from the tip was a different colour for every class. Neat stuff