Never edit the files in your main game directory directly. Copy WEAPONS-PLAYER.rpf into a folder named mods within your GTA V directory. OpenIV will read from here first, keeping your original game files "clean".
Copy the relevant RPF archive (often found within update/x64/dlcpacks/... ) into this new folder. WEAPONS-PLAYER.rpf
Using OpenIV and a custom .meta injection: Never edit the files in your main game directory directly