I'd be tempted to allow augments to give regeneration and perhaps a few other more powerful special qualities as later level and maybe also the ability at or around level 20 to take on two aspects at once. I'm unsure on how this would play out balance wise (100%). I am admittedly looking at the class with only a glance at the spell-casting how ever I doubt even both of those upgrades would add too much more in the way of power compared to the high-level spells you'll also have at those levels.