Press Square, Triangle, Circle, Left, Up, Right, L2, R2 at the main menu.
Level skip with Silent Assassin rank and special weapons:
Press R2, L2, Up, Down, X, L3, Circle, X, Circle, X during game play when a
level first starts.
When you are killed, the screen will turn black and white briefly. Try to
shoot four people in the head while this is happening to resume playing with
barely any health.
Successfully complete the indicated mission with a "Silent Assassin" rank to
unlock the corresponding weapon.
CZ 2000 Dual Pistols: Mission 1
Micro Uzi Dual Submachine Guns: Mission 2
Silverballer Silenced Dual Pistols: Mission 3
Magnum 500 Dual Pistols: Mission 4
Sawed-Off Shotgun Dual: Mission 5
M4 Carbine Silenced Assault Rifle: Mission 6
SG220 .S Dual Pistols: Mission 7
MP5 Silenced Submachine Gun: Mission 8
AK 74 Silenced Assault Rifle: Mission 9
GK 17 Dual Pistols: Mission 10
Micro Uzi Silenced Dual Submachine Guns: Mission 11
PGM Silenced Sniper Rifle: Mission 12
All weapons in training level:
Start the training level, then enable the "Level skip" code. You will complete
it with a "Silent Assassin" rank. Choose the training level again, and all the
weapons in the game will be unlocked in the weapons storage area. This also
will unlock the Cardboard Tube weapon.