I tend to think of the double damage bump as belonging to the
element (dive, skyblitz)... But I do love the shieldsmasher idea though. Very gravitesque...
Will it allow smashing of immaterial shields?
What do you think about: "Target creature deals +1 damage per hp and is able to shatter opponent's shield, but now has a 60% miss chance" or you could do +1 damage per N hp instead (where N can be adjusted to help balance it)
(I had to change the wording for the accuracy loss to make it fit)
This gives it more of a gravity feel, giving extra damage based on the mass (hp) of the creature. That fits the
theme a bit better than a raw attack power double, which seems to be the purview of