In Wrath of the Lich King it is item level 245, requires level 80 and is named Nightsong Vestments. 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 Vestments Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Conqueror's Nightsong Vestments suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Conqueror's Nightsong Vestments Fits
Other Items Named Conqueror's Nightsong Vestments
1 other item in the current build is also called Conqueror's Nightsong Vestments. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Items Numbered Next to Conqueror's Nightsong Vestments
Blizzard numbers items as they are created, so the named items next to ID 46194 (46189 to 46199) were usually added in the same batch as Conqueror's Nightsong Vestments: the same quest line, zone, vendor or reward set.