Aqua's charm was unbreakable. They were the reminder of her unbreakable friendship, and nothing could break the strong metal frame, carefully reinforced with magic. The glass, however . . .
Aqua bitterly realized that her star charm was just like her friendship. Strong and unbreakable. But made of shattered glass.
Namine's charm was fake. She stared sadly at the yellow star, remembering something Larxene had told her about yellow being the color of evil. But she wasn't trying to be evil, and she wasn't trying to be fake. Yellow was the color of evil, but it also was the color of the warm, life-giving sun. Couldn't something mean more than one thing? She hoped so. Stars, no matter what color, symbolize friendship, strength, and protecting what needs to be protected. A fake friendship, something inside her whispered. Twisted realities, warped memories, false truths, how could any of that be good? Namine shivered and held the star closer to her.
Kairi's charm was happy - a reminder that even in the darkest times, there was still hope, still something to hang on to. She slowly traced the edges of the farm. Sora was the smile. Riku was the strength of the shells. And Kairi was the string that held everyone together.
Xion's star charm was disassembled, a half-finished creation of shells. She had seen it in a dream, it - it - it's my lucky charm, be sure to bring it back to me - it meant that friendship was stronger than distance or pain. She had tried trying the colorful shells together with some twine, but when the twine didn't break, the shells did. Xion blinked tears out of her eyes, and tried one more time. If she could try just a little harder, maybe she could finish a charm. Maybe she could find a way to hold it together. Maybe she could...
The stars in the sky were broken, too. But, Sora, alongside Riku, was slowly putting them back together. When Sora had first landed in Traverse Town, nearly all of the stars were broken and fading, and a few had disappeared. Now, even though there were rather bruised, broken, and shaken about, they were healing.
Sora held many stars in his heart. He was the sky that held all the stars together.
One sky, one destiny.
Author's note: We've seen that stars are important in Kingdom Hearts. And when "Sora" literally means "Sky", and when you consider the significance of Riku pointing out that every star is a world, and they're all connected by one great big sky (not to mention Kairi's "one sky, one destiny"), I think I see some serious foreshadowing for Kingdom Hearts 3.
I actually wrote the last part first, then realized that stars are very symbolic of not just Sora, but of friendship and connections, so I added on the previous sections. I liked narrating from the point of view of the girls, because they are often ignored in favor of the other characters, but their roles are really interesting and important.