In Wrath of the Lich King it is item level 245 and requires level 80. In MoP Classic it is item level 245, requires level 80 and sells to vendors for 1c.
In the Appearances collection, Relentless Gladiator's Shiv is listed as Vendor. Appearance ID: 10891. No other item uses this appearance, so it is unique to Relentless Gladiator's Shiv.
Read from the World of Warcraft client build files.
How Relentless Gladiator's Shiv Compares
Who It Suits
In their in-game specialization descriptions, these specs name daggers among their preferred weapons:
Items Numbered Next to Relentless Gladiator's Shiv
Blizzard numbers items as they are created, so the named items next to ID 42250 (42244 to 42256) were usually added in the same batch as Relentless Gladiator's Shiv: the same quest line, zone, vendor or reward set.