In Wrath of the Lich King it is item level 245, requires level 80 and is named Deathbringer Leggings. In MoP Classic it is item level 232, requires level 80 and sells to vendors for 1c.
Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Conqueror's Deathbringer Leggings Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Conqueror's Deathbringer Leggings suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Conqueror's Deathbringer Leggings is part of the transmog set Conqueror's Deathbringer Garb (Warlock only). The other 11 pieces:
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Conqueror's Deathbringer Leggings Fits
Other Items Named Conqueror's Deathbringer Leggings
1 other item in the current build is also called Conqueror's Deathbringer Leggings. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Items Numbered Next to Conqueror's Deathbringer Leggings
Blizzard numbers items as they are created, so the named items next to ID 46139 (46134 to 46144) were usually added in the same batch as Conqueror's Deathbringer Leggings: the same quest line, zone, vendor or reward set.