In Wrath of the Lich King it is item level 251 and requires level 80. In MoP Classic it is item level 251, requires level 80 and sells to vendors for 1c.
In the Appearances collection, Relentless Gladiator's Endgame is listed as Vendor. Appearance ID: 7160. 31 other items wear the same appearance; 11 of them are listed here.
Read from the World of Warcraft client build files.
How Relentless Gladiator's Endgame Compares
Who It Suits
Relentless Gladiator's Endgame carries Intellect, the primary stat of Holy Paladin; Discipline, Holy and Shadow Priest; Elemental and Restoration Shaman; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock; Mistweaver Monk; Balance and Restoration Druid; Devourer Demon Hunter; Devastation, Preservation and Augmentation Evoker.
Similar Items
The 10 items nearest to Relentless Gladiator's Endgame (item level 35) in item level among Armor > Miscellaneous, Held In Off-hand slot, from item level 29 to 38.
Items Numbered Next to Relentless Gladiator's Endgame
Blizzard numbers items as they are created, so the named items next to ID 42527 (42520 to 42536) were usually added in the same batch as Relentless Gladiator's Endgame: the same quest line, zone, vendor or reward set.