Two player mode:
Press Z to display the weapon menu. Hold X and press L. A second Leon that is usable by controller two will be added when both buttons are released. Entering the code again will return the game to single player mode.

Hint: Multi-hit dive attack:
Hold C then press B For a special multi-hit dive attack only with the mace and great sword. You will jump and come down with an impressive multi-hit attack.