One swing lop the top of the botle, one more swing lop the middle off to turn one normal bottle into 3 bottle bits Samurai's don't saw
No, but seriously, take a sharp kitchen knife, increade the sharpness considerably, and make the blade out of super strong carbon steel instead of weak stainless steel, and your about there.
Bottles are easy. Anyone can cut a bottle with a sword like that, but cutting something harder requires technique and that is what i am learning. Kendo - the martial art of the sword.
With very very good technique, you could probably take the stainless steel pretend sword that ab1385 posted as an ebay link above and slice it's blade completeley in half (kill bill style). It would blunt my sword quite quickly though and you do run the risk of damaging my sword quite badly if you get it even slightly wrong.
Fun.
Butuz