Does anyone know who drops these?

Seems to be a drop off Gathios the Shatterer (Illidari Council), from Black Temple.
http://www.thottbot.com/c22949

These leggings are sold in The Seer's Library, by Veynna Darnstar <Keeper of Sha'tari Heirlooms>.  But it doesn't say what items you need in order to purchase them.  What items are needed, and where do you get them?

so if i get it where am i suppose to bring it to trade it in???

if you dont know... you arent progressed enough that you NEED to know.  once you enter the hyjal instance there is a vendor for all t6.  you need to have gone to hyjal before ever going to BT.