The ones who carry the blue crystals do so under the flag of a benevolent being.
The ones who carry the purple crystals do so under the banner of a creature of chaos.
Green is the neutral color for those who recognize both deities are the same celestial beast.
The blue one's symbol looks off, but I have no motivation to change it
I may, however, change purple to red and green to white - make it more into a fire and ice sort of thing