D&Dtools1

An icy burst weapon functions as a frost weapon that also explodes with frost upon striking a successful critical hit. The frost does not harm the wielder. In addition to the extra damage from the frost ability, an icy burst weapon deals an extra 1d10 points of cold damage on a successful critical hit. If the weapon's critical multiplier is x3, add an extra 2d10 points of cold damage instead, and if the multiplier is x4, add an extra 3d10 points. Bows, crossbows, and slings so crafted bestow the cold energy upon their ammunition. Even if the frost ability is not active, the weapon still deals its extra cold damage on successful critical hit.