The game's collection data lists Firebird's Tunic as sold by a vendor NPC in Warspear.
Vendor
Zone
Map
Waypoint
Other items it sells
NPC #88569
Warspear
-
-
166
Vendor NPC, zone and position come from the client's collection source tables (CollectableSourceInfo and CollectableSourceVendorSparse); coordinates are the in-game map readout.
Build history
First seen in build 5.5.4.69585 (Mists of Pandaria).
Read from the World of Warcraft client build files.
How Firebird's Tunic Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Firebird's Tunic suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Similar Items
The 10 items nearest to Firebird's Tunic (item level 40) in item level among Armor > Mail, Chest slot, from item level 32 to 46.
2 other items in the current build are also called Firebird's Tunic. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Blizzard numbers items as they are created, so the named items next to ID 87129 (87124 to 87134) were usually added in the same batch as Firebird's Tunic: the same quest line, zone, vendor or reward set.