For context, I have probably the best PC build I could have for this specific part of the game. That said.. once I had a lvl 7 PC, I came back with just Carth and first-tried the fight. Just put a shield on each and went to work. No other items. Killed her about round 5. Thought that might've been a fluke because she didn't heal for whatever reason so I tried it one more time. The second time was harder. She used both her life support packs, but still, I went through one full shield and it was over. Third time was very similar to the second. Fourth time I killed her on round 4 and she didn't heal again. Fifth time, same story. The times she chooses to heal seem to be somewhat random but often don't occur until at least round 4 (got round 3 once in 8ish go's at her). If I had a third party member I'd be killing her consistently by round 3. Overall, she still needs an extra oomph. To reach your desired difficulty, either a health or a defense upgrade is a must. Also (I think you'll like this one), instead of a concussion, I'd just give her a thermal detonator, in order to give her the possibility of taking out one of your companions almost, if not immediately (and make it so that you absolutely have to dodge it, which again, I do like the idea of). Might even consider giving her a shield on top of that, as keeping her with her blaster out is about half as hard as the alternative. I did give it a try on Normal difficulty as well, and I'm sorry to say it was painfully easy. With Zaalbar and Carth in my party, I used no items whatsoever and just let the game play itself (letting the AI control my entire squad). Even with her healing both times, she was still dead by round 8, with none of my squad going down, or even being below half HP for that matter. So at this point, even on impossible, with only two party members (if we're being honest, I could, within reason, just solo her as long as she doesn't take her vibroblade out), I'm not having to use stims, mines, grenades, or even micro all that well. One last change I'd like to see is giving her weapons a slight buff. Right now, her blaster is barely better than Bendak's, and her vibroblade is worse than the prototype. I'd say she still needs some, calibrations.
Oh yeah, not sure what that 3 damage was all about earlier. Didn't get that this time.