If anyone wondered why suddenly Shion trembled after Zech reveal her secret as spy, it because Zech cast "Confusion" mind magic to her so she immediately panicked and easily show her vulnerability.
Finally, I kinda hate this amnesia arc especially because Celeste forgot about her son. I don't really care about drama bullshit (because it's common thing in every amnesia arc) but she forget her son is really sad for me knowing she really love him.