Need some help....
I don’t know about the coat, but the mask and shoulderpads are called “Gunner’s Pauldrons” and the mask is called “Needname Mask”. They are part of a set that doesn’t have a consistent name. You can try them on at the PvP locker in the mists though.
If you’re looking for the skins, head to the Iron Marches. You’ll find all the pieces through Renown Hearts / Karma Vendors.