Go to the unlockables menu and enter the respective code for the unlockable you desire.

Bone Cleaver Variation Art: Press the left Analog stick down, press X, press Right Analog stick down, press Y, LB, LB, Down, Down.

Cave Ape Variation Art: Down, LB, Down, RB, X, LT.

Conan Helmet Study #1: Y, Y, Press Left Analog stick, X, X, Press Right Analog Stick, Up.

Conan Helmet Study #2: Up, LB, Down, RB, X, X, Y, Y, Press right analog stick.

Giant Sea Serpent #1: Press Left Analog Stick twice, Y, Y, X, Press right analog stick.

Giant Sea Serpent #2: Left, X, Left, Y, Down, Press Right Analog Stick twice.

Graven Variation #1: Up, Down, Up, Down, Left, Right, Left, Right, X, Y.

Graven Variation #2: Up, Down, Left, Left, X, X, X.

Spirit Variation: Right, Right, Left, left, Up, Down, Up, Down, X, X.