So everybody knows that the best stuff in legion are the legendary weapons. Of course there is no way to add the same legion system for them but here's my opinion.You can do the same think you did with the transmog system but the legendary weapons could drop from the high level bosses( heroic dungeons and raids) with aroun 1% drop chance...and maybe you could update the mout models becouse you already updated the characters and now the moutns look stupid...(sorry for my english).