In Wrath of the Lich King it is item level 245, requires level 80 and is named Nightsong Leggings. 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 Leggings Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Conqueror's Nightsong Leggings suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Similar Items
The 10 items nearest to Conqueror's Nightsong Leggings (item level 35) in item level among Armor > Leather, Legs slot, from item level 29 to 39.
Items Numbered Next to Conqueror's Nightsong Leggings
Blizzard numbers items as they are created, so the named items next to ID 46185 (46180 to 46190) were usually added in the same batch as Conqueror's Nightsong Leggings: the same quest line, zone, vendor or reward set.