Whilst using a crystal as a weapon may be a novel idea using an aetheryte would fundamentally be the same as any other caster using aether to cast magic. BLMs draw on the aether in their bodies, WHMs draw on the aether in the world around them and SMNs draw on ambient elemental aether, using special inks to shape it using patterns rather than their minds as the mages do.

The machinist will actually be aether based as well since their hand cannon is magitek and powered with aether/ceruleum cartridges.

I could certainly see some form of crystal as an interesting weapon choice for a future job though.

A Machinist summoning gun would be really cool too!

I can haz Runic Blade? Kinda sounds Rune Knight-ish...