If I didnt know this then there has to be a great deal of other players that were unaware of this. Had I known I would have definately capped every week so I could get a full feral and boomkin set, and not have to wait for the next season to start. So basically if your class' specs use a different set of armor, after 26k conquest (full grievous for main spec) The vendors adjacent unlock and purchasable grievous gear for honor is available.
Im sure many people knew this long ago. But I didnt and Ive been playing for a very long time. Hope others find out about this!