Upgrade the indicated weapon fully to unlock the corresponding bonus weapon for purchase from the shop.
Gatling gun for Chris: Fully upgrade the VZ61 machine gun.
Hydra triple barrel shotgun: Fully upgrade the Ithaca M37 shotgun.
Longbow for Sheva: Fully upgrade the S75 rifle.
M93R pistol (Samurai Edge Custom): Fully upgrade the M92F pistol.
Smith and Wesson M500 Magnum (Handcannon): Fully upgrade the Smith and Wesson M29 Magnum.