In The Burning Crusade it is item level 123 and requires level 70. In Wrath of the Lich King it is item level 123, requires level 70 and sells to vendors for 1c. In MoP Classic it is item level 123, requires level 70 and sells to vendors for 1c.
Read from the World of Warcraft client build files.
How Marshal's Silk Footguards Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Marshal's Silk Footguards suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Marshal's Silk Footguards is part of the transmog set Aldor Regalia (Mage only). The other 10 pieces:
Blizzard numbers items as they are created, so the named items next to ID 29003 (28998 to 29008) were usually added in the same batch as Marshal's Silk Footguards: the same quest line, zone, vendor or reward set.