You can glamour your weapons anyway, for the most part they're almost aesthetic in the weapon type; a Fire Mage using a sword is functionally not any more different than a fire mage using a staff.

I haven't checked the updates lately, but iirc you can change your relic path before level cap (versus getting a second one).

I also do not recall them explicitly saying that the artifact weapon is only for this expansion. If it was, then that's really a silly design to put as a form of character progression that's only present for levels 100-110.