Deathfrost

Permanently enchant a melee weapon to cause your damaging spells and melee weapon hits to occasionally inflict additional Frost damage and slow the target. Slow effect does not work on targets 73 or higher.

Source

 * Formula: Enchant Weapon - Deathfrost drops from Lord Ahune in the Slave Pens during the Midsummer Fire Festival.

Suggested use
Useful as a mid priced enchant for leveling between 60-70. Situationally good for tankadins when a warrior is not in the party and minimizing damage is more important than threat. Good in PvP or on a backup weapon. Enhancement Shaman get the most benefit from this enchant (there has been some argument that Shadow Priests are also a good choice). Whatever your class, another more costly enchant exists that is superior to deathfrost.