Here are the list of the unlock able blades.
Disco Blade: Slice 50 Banana's.
Mr. Sparkle Blade: Slice 3 Pineapples in a row, in Classic Mode.
Old Glory Blade: Finish a game with a score of "50" points.
Butterfly Knife Blade: Get a combo with strawberry 40 times.
Flame Blade: Score a combo after the timer ends in Zen Mode.
Ice Blade: Slice 20 Freeze Banana's in Arcade Mode.
Shadow Blade: Get a score of at least 175 in Zen Mode, playing upside down. (Device is right way up)
Pixel Love Blade: Get 50 Combos in Classic Mode.
Piano Blade: Slice 100 Critical's.
Party Time Blade: Slice every strawberry and nothing else in a game of Arcade Mode.
Bamboo Shoot Blade: Play a Full Game of Zen Mode everyday, 5 days in a row.
Added by: Cyndevia Feb 25th 2011, ID#181