To me, a clear example of why the Second Amendment should have been better defined is that Judge Scalia interpreted the Second Amendment to apply to any weapon that you could physically carry. By his interpretation, cannons are not protected by the Second Amendment, but handheld rocket launchers are protected. Basically, if you are physically strong enough to carry the weapon it is given protection under the Second Amendment by his interpretation. Even if his interpretation is precisely 100% correct, the Second Amendment still should have been better defined because there are so many plausible arguments against interpreting arms protections given by the Second Amendment as being what you can physically bear/carry in your arms.