config.ini is one of the main configuration files of Vendetta Online, along with wgaf.cfg. It is found in the base Vendetta directory, which is
~/.vendetta/ on Linux,
C:\Program Files\Vendetta Online\ on Windows, and
/Applications/Vendetta.app/ on OS X.
Within the config.ini file you will see a label for any joystick that has been connected to your computer when you have played the game. These are added automatically every time you plug in a new device, and old ones can and will clutter up the file if you do this frequently.
If you want to change a button to a bind, they behave differently than the keyboard binds. You cannot add joystick configurations to a filename.cfg file and load it, you must change the config.ini file directly. You must also do this while the game is not running as the config.ini file is often updated and overwritten by the game during the course of play.