It's pretty simple, just equip yourself with a weapon that has this feature and press the key to switch to the secondary weapon.
How do I use the weapons with dual function or special ability? This will equip the weapon with infinite ammo in your inventory. To obtain in-game weapons, type the name of the weapon you wish to have (the weapons have the same names as their respective champions). This mod adds 55 new weapons to the game, each one with different attributes based on the original weapons of the video game Paladins: Champions of the Realm. If you want to have a pleasant gaming experience, it is always advisable to opt for the original video game rather than this mod. This mod is an adaptation / interpretation of the weapons of the video game Paladins: Champions of the Realm, which aims to bring to Grand Theft Auto: San Andreas an imitation of the aforementioned weapons. Paladins Weapon Pack by ElNepeDeMaeve & MasterMRL