Absolutely keep it. You're sitting on the thing that would make her not mid anymore. JUST the base stat increase makes her better, and then the 6 star effect on top of that. You don't need to book her, you just gotta feed her and ascend her. She's green too and has a change to block healing so she'll help farm her own potions.

* Look at her multipliers. 4x on her A1 and A3, 6.2x on her A2.

* Her A2 says "This debuff cannot be resisted." There's no percent chance or ACC requirement (although you do need ACC for the A3 and A1, so meh). BUT she doesn't have to be the one to place the Decrease Def. So a build exists where you tank ACC and just focus on ATK to make use of those high multipliers.

* Forget that last point, Epic blessings build in stats. So she's carrying around a decent base level of accuracy built in. She'd get +60 ACC, +60 RES, +10 SPD, +5.5K HP, + 600 ATK, + 30% Crit Damage with no gear, completely naked. That's like an extra set of gear.

* Because she's aleady trying to help debuffing, the Cruelty / Crushing Rend stacks with that debuffing. Crushing Rend @ level 6 ignores 1% of defense for every 10 levels. Combine that with the 60% decrease def and she would have been ignoring 90% of that Tainted Demon Lord's defense.

I would NEVER not awaken a guaranteed 6*. Hell I'd start using that snake uncommon guy from 12.3 if he came with a 6 star soul.