This item is acquired in-game. See its sources below.
Not sold on the Auction House·Miscellaneous
An Epic Miscellaneous, item level 30, requires level 30, binds when picked up. Drops from Blood-Queen Lana'thel in Icecrown Citadel and 4 other encounters.
The lowest listed price among them is Plain Letter at 1 silver in the US Auction House.
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Protector's Mark of Sanctification Fits
Other Items Named Protector's Mark of Sanctification
1 other item in the current build is also called Protector's Mark of Sanctification. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Items Numbered Next to Protector's Mark of Sanctification
Blizzard numbers items as they are created, so the named items next to ID 52026 (52021 to 52031) were usually added in the same batch as Protector's Mark of Sanctification: the same quest line, zone, vendor or reward set.