Rank 13 Priest sets
Rank 13 of 14 · Field Marshal / Warlord · 2,650 Rank Points · the rank unlocks elite chest upgrade and elite helmet upgrade
4 sets Forever built for priests here — 24 pieces
Pieces Classic’s item table never had, in named sets that carry no rank requirement of their own. The rank is the rank title each set is named after.
Alliance
Field Marshal's Investiture 6 pieces
Horde
Warlord's Investiture 6 pieces
6 older armour still gated at this rank
Classic’s own rank gate, which Forever has not rewritten. Not a reward this rank hands out.
The client gates these at rank 13 through ItemSparse.RequiredPVPRank, and
AllowableClass is what puts them under Priest. Read from the Forever client, build 1.60.1.69893.
That gate is not the same as the rank's unlock, and what a vendor hands over is server-side.