Patch 5.4 means the end of Arena Season 13 and arrival of the last Season 14 that will last until the next expansion is released. But worry not, for we will most likely see the patch go live in 2 or three months from now.
In Build 17056, sets for 10 classes have been added. Here they are listed class by class. There are three recolors available for each class set. Images are courtesy of MMOChamp.