User blog comment:Mexican spider/Gray Fox VS Master Ferroda/@comment-2254913-20100917225108/@comment-422690-20101112134520

... It can. The only whay a lightsaber can't cut a normal sword is if it is laced with Cortosis or Phrik, or made using an alloy of either of the two metals. Since those are not found on Earth, it is safe to assume that Grey Fox doesn't have them.

In short, the anon is wrong.