Radical Idea but how about taking the hammer 3 abilities and making them flip over skills on the attunements, similar to tempest overload? Then you can add one new weapon skill per element, hopefully at least two that create their own fields, like a line of rocky spikes shooting forth for earth, an erupting fire wave in fire? That way hammer isn't entirely reliant on the jade sphere which is supposed to be the "wells" we were promised. Catalyst doesn't have any utilities for creating fields other than from the conjured weapons like lava axe.
Though maybe you could keep the weapon skills the same and use the flip over attunement skills as 4 separate jade sphere skills, one for each of the "wells", that way your not forced to use the fields of the new attunement when you probably dot want to. Hammer should really be all melee auto chains too. If it's gonna be a melee spec then make it a melee spec and revert air 1 and fire 1 to melee skills, none of the other skills would have to change either.
The aura traits seem pretty bad as well, I'd like to see empowering auras replaced with another trait the allows augment skills to apply an aura based on current attunement when used. Maybe as a grand master trait, with staunch auras moving down to the master traits as I believe it would be more in line with the power provided by those traits. Augmented Auras seems like a good enough gw2 trait name.
I also think Elemental Celerity should apply to all skills(except attunement) rather than just weapon skills, raise the CD if you need to. The fields from the Jade Spheres should give you Stab/Earth, Quickness/Air, Alacrity/Water and Fury/Fire as well. Might and resolution aren't that big of a help when its now constant, so the spheres should provide more lucrative boons considering its CD and Energy requirement.
TLDR; All auto attacks should be melee skills, jade sphere should be 4 skills that flip over on attunement swap, sphere fields need more lucrative boons, and augment skills should have trait/s that improve them.
Also, save the High damage single target abilities for the Longbow Arcanist coming in the next expansion after EOD please...can't wait.