• Observer's Mantle
• Item Level 226Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Mail
• Shoulder
• 985 Armor
• +59 Stamina
  +60 Intellect
• Red Socket
  Blue Socket
• Socket Bonus: +6 Critical Strike Rating
• Durability 85 / 85
• Requires Level 80
• Equip: Improves critical strike rating by 46.
  Equip: Improves haste rating by 50.
  Equip: Increases spell power by 100.
• Sell Price: 10 40 12

Source

This item can be found inside Gift of the Observer after defeating Algalon the Observer in the 10-man version of Ulduar.

Patch changes

• Patch 3.1.0 (14-Apr-2009): Added. 
  

External links

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB