Square Enix What is up with Sephiroth's (and Cloud's) sword?

Was it that thing about the great Masamune who made extremely strong swords and Murasame who was his student that got to be famous because he made extremely sharp swords? That sounds somehow familiar.

 

Well.....kind of a simple question....the reason why? Cloud's Buster Sword looks like it should only be in display at some museum. If not, i believe that his sword is a Murasame Blade sword. The only sword for cloud that ever made sense to me was Ragnarok. And by the way, Sephiroth's sword is a Masasume style and (as stated before) can only be handled by sephiroth.