Bring Nekrum's Medallion to Thadius Grimshade in the Blasted Lands.
I'll find out where your gryphon is, but first you have to do something for me. There's a troll in Zul'Farrak, Nekrum Gutchewer, who possesses a medallion I would very much like to study. Bring me that Medallion and I'll use my powers to find Sharpbeak.
Zul'Farrak is across the ocean to the west, in the desert of Tanaris.