I couldn't decide whether to label this as a warrior transmog or as a paladin transmog so I just put "plate" in the title. This is, needless to say, available for all plate classes. It would, however, be slightly easier to get as a warrior, since the shoulders are just a replica of the t12 warrior shoulders.
The male model of this chest piece shows an open back just like the female version to the left does. If you don't like showing too much skin you can hide it with a tabard or cloak.
[Bloodscale Helm] , Head
[Spaulders of Recurring Flame] (heroic), Shoulders
[Bloodforged Chestpiece], Chest
[Rockwurm Plate Handguards], Hands
[Thorium Belt], Waist
[Greaves of the Martyr], Legs
[Lavawalker Greaves], Feet
[Liar's Tongue], One-hand Sword
[Ward of the Red Widow], Shield