Nothing really special, though it looks nice. I’ll admit it was rather easy to make, since I used the boolean modifier to help me crack the sword apart. I also use Game Engine rigid body physics to drop the pieces “realistically”.
I know the shattering itself isn’t realistic; if an actual glass sword were dropped the blade would be most likely to be obliterated. But then it wouldn’t look nice, would it?
This was my 3rd revision after someone gave CC. You can see my first two below; all that’s different is the floor:
http://img713.imageshack.us/img713/2329/shatteredbladehd.png (Version 1)
http://img30.imageshack.us/img30/4456/shatteredbladehdmarble2.png (Version 2)