In Wrath of the Lich King it is item level 232, requires level 80 and is named Malfurion's Leggings. In MoP Classic it is item level 245, requires level 80 and sells to vendors for 1c.
In the Appearances collection, Malfurion's Leggings of Triumph is listed as Boss Drop. Appearance ID: 11777. 15 other items wear the same appearance; 12 of them are listed here.
Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Malfurion's Leggings of Triumph Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Malfurion's Leggings of Triumph 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
Malfurion's Leggings of Triumph is part of the transmog set Malfurion's Battlegear (Druid only). The other 16 pieces:
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Malfurion's Leggings of Triumph Fits
Other Items Named Malfurion's Leggings of Triumph
1 other item in the current build is also called Malfurion's Leggings of Triumph. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Items Numbered Next to Malfurion's Leggings of Triumph
Blizzard numbers items as they are created, so the named items next to ID 48135 (48130 to 48140) were usually added in the same batch as Malfurion's Leggings of Triumph: the same quest line, zone, vendor or reward set.