I feel like removing her arcane would make her an essentially useless legendary at higher levels especially with other AOE true damage legendaries (that can also create mana and heal themselves depending on which ones). While it’s true she can become very strong, if you’re running the queen mab deck that you always suggest (Sooth/Sooth/Valk/Queen or Sooth/Queen/Valk/Queen) then you had quite a few turns of building her up to get her to that one shot potential, which is kind of the point of any arcane trait caster. I wouldn’t say that a case where you sacrificed 3 cards and multiple turns (plus damage on queen) to get a large aoe off is a good example for a reason of nerfing her.
Anyway, with cards like crimson bat and maw existing, it’s just going to be a jump from 1 card to the next for what needs nerfing. There are quite a few cards that need nerfed if we’re truly trying to make a level playing field, and even then it’s not level cause human vs ai.
The best I would say to do is drop her extra turn because with valkyrie and a pretty easy setup, you can get her spell off twice in a single turn, sometimes even getting her mana full again before the AI has a chance to react.