Checking out a Trophy FAQ for SSBM I came upon this:
The Master Sword actually first appeared in the Legend of Zelda for
NES. Most will say the third sword is not the Master Sword, it's the
Magic Sword. If you were lucky enough to get one of the original
copies (the first 200 copies that came out with the system) then when
you talk to the guy who says something about it, he calls it the
Magic Sword in the first world and the Master Sword in the second
world, and it is slightly stronger in the second world. So, if you
want to get really technical, that was the first appearence, even
though the game doesn't fit into the storyline, but it was the first
one released.
http://www.gamefaqs.com/console/game...ame/32502.html
"Trophy Guide"