Wikia

Rune of Razorice
Rune of Razorice 5 sec cast Requires One-Handed Axes, Two-Handed Axes, One-Handed Maces, Two-Handed Maces, Polearms, One-Handed Swords, Two-Handed Swords, Staves, Fist Weapons, Miscellaneous, Daggers, Spears Affixes your weapon with a rune that causes 2% extra weapon damage as Frost damage and increases enemies' vulnerability to your Frost attacks. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
Usable by
Class	Death knight
Properties
Type	Utility
School	Physical
Cooldown	None/Global Cooldown
Other information
Requirements	Requires One-Handed Axes, Two-Handed Axes, One-Handed Maces, Two-Handed Maces, Polearms, One-Handed Swords, Two-Handed Swords, Staves, Fist Weapons, Miscellaneous, Daggers, Spears

Rune of Razorice is a Death knight frost rune that can be made through runeforging.

good choice as an offhand rune for frost deathknights as much of their damage comes from frost.

Patch changes

Patch 3.3.3 (2010-03-23): Now stacks 5 stacks of 2% Frost Vulnerability instead of 10 stacks of 1% Frost Vulnerability. Proc chance changed to 100%.
Patch 3.2.0 (04-Aug-2009):
- Each death knight can now have his or her own copy of this debuff on the target.
- Corrected a bug where this applied to frost damage done by others.
Hotfix (2009-04-01): "
- The debuff caused by the Rune of Razorice is no longer dispellable.
- The weapon enchants Rune of Razorice and Rune of Lichbane will no longer cause the Killing Machine talent to be triggered more often."
/ Patch 3.0.2 (14-Oct-2008): Added.