• Belt of Merciless Cruelty
• Item Level 200Disenchants into:
  [Abyss Crystal]: 1
• Binds when picked up
  
• Mail
• Waist
• 922 Armor
• +48 Agility
  +92 Stamina
• Yellow Socket
• Socket Bonus: +4 Agility
• Requires Level 80
• Equip: Increases your critical strike rating by 51.
  Equip: Increases your haste rating by 40.
• Sell Price: 5 64 78

Source

This item drops from The Black Knight in the Trial of the Champion on normal mode.

Patches and hotfixes

Patch 3.2.0 (04-Aug-2009): Added. 

External links

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