Well since skystone is soft like lead anyways, it wouldn't make a very good anything on its own. The sword would be many alternating layers of skystone and steel, giving it almost (but not exactly) zero weight, the strength of steel, and the thin layers of soft skystone would absorb the force of impacts. The character I'm almost done writing now uses skystone armor to make herself have (almost) zero weight as well, and her main form of attack would be to launch herself and her massive sword heigh into the sky and come crashing down using gravity and momentum to fuel a single, cataclysmic blow. It's kind of centered around the idea that mass doesn't affect the speed of a falling object or whatnot. Am I still breaking and laws of physics? It never was my best subject. :confused