The Dark side of the Frost moon (6.7 World Quest Spoiler)
Let me preface this by saying that this is just purely a rabbit hole that I jumped into based on very limited knowledge and would be very happily proved wrong.
In Moongazer Columbina says: “The lunar core, the source of the moon's power, became artillery fire aimed at Teyvat.” but is that accurate?
As far as I’m aware, the frost moon seems to be tidally locked to Teyvat. My basis is the fact that when you skip time on the moon, you only see teyvat rotate and it never moves across the moon’s horizon. This means that the surface you see of the frost moon from Teyvat is always the same no matter where you are. This would then mean that because the Dark fortress and subsequently the Moon Weapon is located on the dark side of the moon it never faces Teyvat and is instead aimed outside of it.
Obviously there were initially three moons. The three celestial bodies probably affected how they orbited Teyvat and now that there’s only the frost moon that may have resulted in the frost moon becoming tidally locked. I’m not smart enough to know how the removal of two celestial bodies affects the third’s orbit of the planet but I would assume that they would influence each other.
We know Nibelung converted the three moons into weapons and that HP destroyed Iridescent and the eternal moon as a result and throwing the frost moon out. What if Iridescent and Eternal were actually aimed at Teyvat but frost was aimed outside of it which warranted HP destroying them and simply throwing the frost moon out instead of completely destroying it because it adds another layer of protection against the abyss considering it’s aimed away from Teyvat.