so cant we tell blitz if joyz = 0 fire both weapons
nope, that won't work. As you already found out, the triggers compete with each other in opposite directions, so having both pulled is the same as none pulled.
I know this is getting away from the original post, however. I know there *is* a way to split the triggers, but I don't know how it is done. I have played a racing game where this works. By splitting the triggers, you can keep the gas pressed and use the brake at the same time. If the triggers are not split, then pressing the brake will also take away the gas pedal.
Also, off topic to the original post, but as for configuring different sticks, it seems like every single one is different, even among the same manufacturer. Check the code archives for the joypad configuration code I have made. It is for b3d, but the basic concept should apply anywhere. This allows you to configure different sticks without having to plan for every option. It can easily be expanded to configure buttons and joyhat() as well.