Blazewing is a non-elite hostile level 81 rare phoenix with approximately 93k health who spawns in The Scorched Plain in Mount Hyjal. He looks just like Al'ar the Phoenix God, and my all time favorite mount in game Ashes of Al'ar. The location he can be found at is shown in blue on the map below.
Blazewing drops Blazewing's Furious Kilt, which are bind on equip item level 346 leather caster pants with two sockets. On my server they sell for approximately 1,000 gold. He also drops around 20 gold, and I imagine for leveling characters killing him yields a hefty amount of experience.
Be careful when you pull him, he spawns pretty high in the air. As you can see in the video below, my husband tagged him but then proceeded to fall off the side of the mountain. Also, if your on a leveling character be careful where you take him out. There are npcs all over the ground under where Blazewing patrols and its easy to get overwhelmed. He also hits pretty hard.