My radical suggestion for fixing Celestial Weapons/Adornments is this:
Delete the weapons entirely and unlock the Augments for the rest of the game; however only do so with a restriction of one augment per god per weapon.
The real problem with the design space of Celestial Weapons is that weapons and weapon adornments are two separate item categories. Since this is the case, it makes it very hard to balance Celestial weapons because if you want them to be good, then its outcompeting two separate sets of items instead of one which is how the rest of the game works.
Of the two parts of the Celestial Weapon/Augment pair;
- Augments are this extremely rich land of unique game effects and powerful ornate possibilities
- Weapons are this lifeless cycle of uniform weapon types just to check the box on every major game mode
Do away with weapons entirely and refund the shards we all spent on them. Would I like to use shoulders of prometheus on my Ymir Brilliant Feathers? That sounds exciting to me, IDK about you. With a restriction of one per, youll never crowd out the preexisting metagame of weapon adornments but you still get to upgrade your gear set in a unique way that still makes it worth it for you to chase old and new weapons.