• Bonereaver's Edge
• Item Level 77Disenchants into:
  [Nexus Crystal]: 1-2
• Binds when picked up
  
• Sword
• Two-Hand
  
• Speed 3.40
• 206 - 310 Damage
• (75.9 damage per second)
• +16 Stamina
• Durability 120 / 120
• Requires Level 60
• Chance on hit: You gain 100 armor penetration rating for 10 sec. This effect stacks up to 3 times.
  Equip: Increases your critical strike rating by 14.
• 
• Sell Price: 10 60 67

Source

This item drops from Ragnaros, final boss of the Molten Core.

Patch changes

• / Patch 3.0.2 (14-Oct-2008): The proc effect is now a buff on the wielder rather than a debuff on the target. 
  
• Patch 1.7.0 (13-Sep-2005): The duration of the Bonereaver's Edge weapon debuff has been lowered, but the frequency of the effect has been raised. 
  

External links

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