Firstly, she only takes an extra 50% damage from critical hits, like Battleborn, as opposed to x3 (+200%) like all other NPC enemies.
Secondly, she’s quite easy to kill with a ranged character. Simply walk backwards firing, that’s it. She’ll usually just get stuck slowly advancing on you, if she teleports to you just keep doing what you’re doing. If you want to be extra cheeky and get her stuck in a skill loop, advance on her until she starts an attack animation then back away, rinse and repeat. You can literally lock her in place, or lock her into one movement/animation, and freely attack her without being attacked back.
Edit: THIRDLY, you can pesudo-stun her into an animation with a melee character as well by circle-strafing her, I did this with Phoebe and @supersawnick has done it with Pendles, apparently Aria’s base movement is too slow to keep up, or at least that is my theory based on what I have observed.
@JoeKGBX I think this may require some attention, I doubt she is intended to be so easily killed by exploiting her movement mechanics, no other boss can be manipulated in this way.