Icebound Sigil
Artificer Attack 1
By etching an arcane sigil upon a weapon, you infuse it with icy cold, giving it the power to freeze foes.
Melee Touch
Target: One weapon or implement
Effect: Until the end of the encounter, any attack that uses the target as a weapon or an implement deals extra cold damage equal to your Constitution modifier. As a free action, the target's wielder can end the effect when he or she hits a creature. That creature is then immobilized (save ends).
Icebound Sigil is a daily power available to swordmages at 1st level.