i was trying to gather all the references to nabu malikata wearing a veil and covering her eyes (as you do) but now i’m starting to suspect that it might be a metaphor for her using the abyss to hide herself from the heavenly principles as she refused to meet the same fate as the other angels.
(and thank you @sailor-rurouni for pointing out this line in nicole’s character story 4, which def makes it sound like she managed to slip through the cracks for a little while without giving up her power)
“exhaust every effort” leaves it wide open to interpretation on just how far she might have gone to protect herself, especially with these lines in flower of paradise lost:
i don’t necessarily think she liked doing this, and she created the khvarena with the intent for her to dispel the abyss during the cataclysm. (just a random side note but her separating a pure shard of her power from herself to combat abyssal contamination reminds me of how rukkhadevata broke off the purest branch of irminsul to create nahida)
anyways she probably only intended to use the abyss to hide herself for as long as possible until she could come up with a way to defy celestia, which ended up being her imparting her knowledge on king deshret. (it kinda sounds like she thought he could become a descender?)
with all that being said, this line about shame and sorrow could align with her regret for possibly being the one to bring the abyss into sumeru:
especially since the nightingale in question is most likely rukkhadevata, who warned nabu malikata when they first met not to try to defy the heavenly principles:
and the final piece of this (which might be veering into red string territory so that’s why i put it at the end) is the color purple. it’s so often associated with the abyss, abyssal energy, abyssal corruption, etc etc.
nabu malikata wore an amethyst crown, the original padisarahs were said to be a beautiful purple that even rukkhadevata couldn’t replicate, the flowers around bayt al-sukr are a pinkish purple, and the veiled (!) figure wearing the amethyst crown in the tcg card is covered in purple.