It's really hard to say.
Earthquake effect is incredibley overpowered. But you do not need one every turn, and rarely need more than 6 to shut down a deck, so the weapon os pretty useless.
My only suggestion would be to remove the effect and replace it with something else, maybe a weak creature spawner. No other weapon utilises this effect, and it would synergize with water perfectly. (Flooding and SoP) Flying weapons spawning several creatures a turn would be pretty awesome, and would need to be looked at to determine if overpowered or not.