So... I saw this, and absolutely agreed with the person that was saying these weapons occupy a specific niche. These weapons are pretty amazing at lvl 7, and I usually use them until 14 on every melee build.
But, like he said, this was purely because of the AoE proc on natural 20. Why don't you scrub the augments for heroic that add freezing blast (for instance) and make it the freezing gale effect instead. That way you could put the coolest effect of any of the elemental weapons and add it to your other favorite weapons.