weapnext
This command cycles through your available weapons to the more powerful weapon (however, once you cycle all the way to your most powerful weapon it will then cycle back to your weakest weapon). This command is typically used with a mousewheel. This cycles in the opposite direction of weapprev.
Ex. If you wanted to set weapnext to cycle upwards through your weapons using the mousewheel you would type the console command bind mwheelup weapnext. Now when you push your mousewheel forward you will cycle upwards through your weapons.