• Polished Dragonslayer's Signet
• Item Level 245Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
• Finger
• +61 Stamina
  +56 Intellect
  +36 Spirit
  +10 Fire Resistance
• Requires Level 80
• Equip: Improves critical strike rating by 53.
  Equip: Increases spell power by 89.
• Sell Price: 4 90 60

Source

This item is obtained from the following quests:

•  [80] A Most Puzzling Circumstance
•  [80] A Most Puzzling Circumstance

Patch changes

• Patch 3.2.2 (2009-09-22): Added. 
  

External links

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