With one of the highest added Cold damage (behind Azurewrath), and the ability to Freeze targets, Frostwind is certainly most effective against enemies that are not immune to Cold, or have low Cold Resist.
Perhaps what is most fascinating about Frostwind is its ability to bestow its user with the ability to use a high level Arctic Blast. Although perhaps not used for its damage output, Arctic Blast is very useful for slowing a large group of enemies at once with cold damage.
From a defense point of view, Frostwind is also helpful against enemies that would use cold against you. It halves freeze durations and gives Absorption to cold damage.
One-Hand Damage: (14-16) To (215-254)
Required Level: 70
Required Strength: 99
Required Dexterity: 109
Sword Class - Fast Attack Speed
+180-230% Enhanced Damage
Adds 237-486 Cold Damage, 6 sec. Duration
+7-14 To Arctic Blast*
Freezes Target +4
Cold Absorb 7-15%
Half Freeze Duration
+25% Increased Attack Speed
(Only Spawns In Patch 1.10 or later)