I was a little surprised to hear that they dropped Chemist/Apothecary because they couldn't nail down a weapon or theme for it.

Here you go: Magic Cannon that converts your body's aether into healing energy, and you can put alchemical ingredients in it to enhance the effect. Done.

Makes sense for a mage, works with the theme of a medicine-user, and it's already supported by existing lore (the machinist lunchbox converts your own aether into electricity to power your robots, plus there's the aether bazooka that gatherers use in Diadem).

It sounds to me like they didn't even try and basically just ended up getting distracted by the idea for Sage once they thought of the idea of flying weapons you control with your mind. Sadly I kind of doubt they'll ever add another healer and even if they do, it's many many years away now.