Ok, correct me if I am wrong. The armor set you can buy one piece from 5 different factions is called the "Stalker's Chain Battlegear" and is this:
http://wow.allakhazam.com/db/itemset.html?setid=749
Where did it come from, was that arena season 1 gear or simply PvP gear from BG's?
I think it was just PvP gear that then dropped to being able to simply buy once you hit honored. Then the season 1 gear became PvP gear that you could buy with BG honor and tokens.
Are my assumptions correct? If they are, then with season 4 about to start, are they going to take the season 1 gear and bump it down to being able to purchase once you hit honored and then take season 2 gear and let you get it with BG honor and tokens?