To get the following results, complete the game and take you dagger (note that you shouldn't have your secondary weapon). Now make a pause and enter the code:
To get secret baby rattle weapon: Left, Left, Right, Right, Up, Down, Down, Up, Up, Down.
To get secret telephone weapon: Right, Left Right, Left, Down, Down, Up, Up, Up, Down, Up, Up, Down, Down.
To get secret swordfish weapon: Up, Down, Up, Down, Left, Right, Left, Right, Up, Down, Up, Down.
To get secret chainsaw weapon: Up, Up, Down, Down, Left, Right, Left, Right, Up, Down, Up, Down.