katanas are very light and maneuverable 2 handed swords, in comparison to a european 2 handed sword.
any sword that uses 2 hands is going to cut better than a single handed sword.
smaller blades also create less drag as they pass through their target allowing cleaner cuts with less force.
katanas are designed for big 2 handed cuts.
they are wielded differently than a normal 1 handed sword.
the europeans had different techniques for 1 handed swords than the chinese did and their sword design reflected it.
all the swords are roughly the same and highly tuned to fit their intended use.
you wouldnt do taiji or xingi with a katana or rapier. not that you couldnt do it but its not what those swords are designed for.
http://www.youtube.com/watch?v=X254e0JZuuU
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Jesus? No, but there is indeed a god shaped hole in the heart of man, why is yours so empty? -- snarf igraine
the original monotheism:
http://en.wikipedia.org/wiki/Phallus