In Wrath of the Lich King it is item level 245, requires level 80 and is named Nightsong Headpiece. In MoP Classic it is item level 232 and requires level 80.
Read from the World of Warcraft client build files.
How Conqueror's Nightsong Headpiece Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Conqueror's Nightsong Headpiece suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Items Numbered Next to Conqueror's Nightsong Headpiece
Blizzard numbers items as they are created, so the named items next to ID 46184 (46179 to 46189) were usually added in the same batch as Conqueror's Nightsong Headpiece: the same quest line, zone, vendor or reward set.