Cairngorm said "Character development? Who is that the only person I know is Aechmea". The only significant development (or regression) in their character was when they decided to remove Ghost's fragments from their eyes.
Oh fun fact! Mercury forms an amalgam when it comes into contact with gold, meaning that part of Phos' alloy is being eaten up by Cinnabar's mercury during the battle.
EDIT: turns out mercury amalgamates with gold even if it is involved in an alloy already, oops. But that doesn't change the...
Do the Lunarians really want to be released from their current form at this point? It's been too long so maybe they've lost track of what they originally wanted, just like Phos. Any ending we get won't be fulfilling. Fuck I've lost track of what the point is anymore too.
Here's my little postulate: Carnelian derives from a Latin word meaning "flesh". As @KyoPa suggests, mercury is representative of Cinnabar and the last treasure, which is carnelian. Phos is now covered in mercury, which means Phos has affectively gained a "flesh mantle" or skin.
My theory is...
Phos is manipulating their gold alloy to move their pieces out of the mercury, it's so beautiful but sad because Phos is now an unhinged uncontrollable monster exhibiting this minute kind of control...quite ironic
I feel like Phos will be the one able to pray for the Lunarians. They have lost everything, and according to Buddhism material attachment and craving for such is the source of suffering. Therefore, they are enlightened and have achieved Nirvana in a way????? Correct me if I'm wrong. Furthermore...