Ok, here's what ya do. first, play through the game with Sora and beat it. Once you've unlocked the ability to play as Riku, play through the game and beat it. DO NOT DELETE YOU'RE ORIGINAL SORA FILE!!! Once you beat Riku's story, reload the Sora file you just beat and start synthesizing treasure rooms. you should get the following cards.
Ansem, Lexeaus, and Utlima Weapon.
Also, if you have beaten Marluxia, go around smaking the treasure dropping things and you should eventually get the One-Winged Angel and Daimond Dust keyblades.
Remember, DO NOT DELETE YOUR ORIGINAL SORA FILE OR NONE OF THIS WILL WORK!!!!!