In Wrath of the Lich King it is item level 245, requires level 80 and is named Nightsong Handguards. In MoP Classic it is item level 232 and requires level 80.
Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Conqueror's Nightsong Handguards Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Conqueror's Nightsong Handguards suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Transmog Sets
Conqueror's Nightsong Handguards is part of the transmog set Conqueror's Nightsong Battlegear (Druid only). The other 16 pieces:
Items Numbered Next to Conqueror's Nightsong Handguards
Blizzard numbers items as they are created, so the named items next to ID 46183 (46178 to 46188) were usually added in the same batch as Conqueror's Nightsong Handguards: the same quest line, zone, vendor or reward set.