I like it the way it is, honestly. Esma is already more powerful than it needs to be. (I've had arguments with my friends about this.) However, I think what Nami said was right. Esma cost can be mitigated by Kaina. Especially considering that it's got the range on it, reducing cast time makes it much cheaper. Nothing beats finishing the cast before they get to you.
Kroggles ensures the living stay living, and the dead stay dead.
Clobberella beats you up.
Teela Brown has a birdie!
Flosshilde communes with the very souls of the damned.
Walsung is actually pretty cool. For a guy made of metal.