Serrated Blades

From wow.incgamers.com

Talent: Serrated Blades
Effect: Causes your attacks to ignore part of your target's Armor and increases the damage dealt by your Rupture ability. The amount of Armor reduced increases with your level.
Statistics: Rank 1 = -186 Armor / +10% damage, Rank 2 = -373 Armor / +20% damage, Rank 3 = -560 Armor / +30% damage.