"Very well. It's a polecy of mine not to stick my nose where it doesn't belong." Balthier said to York. He did find it odd that York spoke to a person who seemingly wasn't there, but as he said, wouldn't pry. Turning back to Edgar, he said, "Espers you say? It would seem our two realms have great many things in common. Indeed, my world also has creatures known as Espers. "In vain glory they arose, spouting challanges to the gods. But prevail they did not." Or so the stories goes. My companions and I actually came across several of these great beasts. Put up quite a fight too. Upon their defeat, their spirit turned into a sigel, alowing a person to summon them at one's leisure. Quite handy.
But back to the topic of Magicite. The stones aren't as nefarious as what you described. They're a natural resource. One problem presents itself with their use, however. There are areas known as "Jagd". When in Jagd, the Skystones are sapped of the Mist they hold, rendering them useless."