In Wrath of the Lich King it is item level 213 and requires level 80. In MoP Classic it is item level 213, requires level 80 and sells to vendors for 1c.
In the Appearances collection, Deadly Gladiator's Plate Helm is listed as Vendor. Appearance ID: 10502. No other item uses this appearance, so it is unique to Deadly Gladiator's Plate Helm.
Read from the World of Warcraft client build files.
How Deadly Gladiator's Plate Helm Compares
Who It Suits
Plate is the armor type Death Knight, Paladin and Warrior wear. With Strength or Intellect, Deadly Gladiator's Plate Helm suits Arms, Fury and Protection Warrior; Holy, Protection and Retribution Paladin; Blood, Frost and Unholy Death Knight.
Similar Items
The 10 items nearest to Deadly Gladiator's Plate Helm (item level 35) in item level among Armor > Plate, Head slot, from item level 34 to 37.
Items Numbered Next to Deadly Gladiator's Plate Helm
Blizzard numbers items as they are created, so the named items next to ID 40823 (40818 to 40828) were usually added in the same batch as Deadly Gladiator's Plate Helm: the same quest line, zone, vendor or reward set.