Melee damage vs frozen non-boss targets is supposed to get a 2.2x multiplier. When using Wormgod Caress, any stacks of Burning Fists will remove all the bonus damage vs frozen targets. This seems to be a bug and has been present since the launch of The Final Shape. This occurs with all melees, not just glaives like Winterbite. Considering we are getting a stasis glaive with Chill Clip, I'd love to see this fixed soon!