I forgot what chapter but they mentioned in season 1 that wings are very intimate and normally only get touched by lovers during sex. Only ML is allowed to touch and groom Mc’s wing which is why he noticed he got horny from it.
I don’t remember which chapter either but I think celestials weren’t combative till Mc changed things and he never had to lift a finger to actually kill or injure anyone.
The wings and neck for celestials are sacred that only themselves or their lovers are allowed to touch. That's why they don't wear anything revealing. MC especially because he's wings sensitive due to do not being born with them basically he has overgrown baby wings reason why he can't fly or fold them away (this wasn’t explain but in the novel it has)
The reason why they are considered weak was because they mainly know for being (in gaming terms) supports that did potions they didn't kill or do any damage to others (they're considered pure) until MC changed them to dark celestial (i don't know if you remember when MC was kidnapped he kills a minion the minion panics because he didn’t think celestial could kill—which celestial aren't known for basically celestial are angels) MC also mentioned that his vessels have high status in potion making but they are no longer able to complete one due to being stronger in other aspects like fighting.

I have been reading this for a while but still wondering..
Why they focused on the wings in the smut scene so often? What does it means? And why touching the wings seems like such a big issue to them? Is it considered as their erotic/private part or something?
And.. why they keep saying something like “you are not pure anymore”. Is hurting others a taboo for celestial? That’s why they originally weak?
Can someone please explain ╥﹏╥