Instructions
Use the thumbstick or directional pad to navigate through menus for either version of the game -- PlayStation 3 or Xbox 360. To select and confirm a choice, press "X" for the PS3 or "A" for the Xbox 360. Highlight and select the "Character Creation" option from the main menu of "Soul Calibur IV."
Scroll through the thumbnail photos of characters until you find Amy. Select Amy to bring up a new screen that tells you to purchase her for 4,000 gold so you can customize her and use her in any mode of gameplay.
Exit to the main menu and select "Single Player Modes." This brings up a sub-menu with options for all of the modes you can use. Select "Story" from the list. At the next screen, you must select a difficulty level. Choose either option, since difficulty has no bearing on whether you unlock equipment.
Select Amy as your fighter. Complete all of "Story" mode to unlock the rest of her equipment. Once you return to the main menu after completing "Story," go back to the "Character Creation" screen. Select Amy and use the "R1" button for either console to get to the "Weapons" tab. Select her current weapon to bring up a list of her other weapons, then buy the ones you have unlocked.