[XP] CLASSES LEVEL INDEPENDENTLY OF ONE ANOTHER

Hello, I'm new here, and I need some help, I've searched and searched, but I cannot find anything that helps me. Anyways, I am trying to create a system where a character can change their class depending on what weapon they have equipped. So far, so good. I can switch my fighter to a mage by just equipping a staff, and with events too. However, whenever I switch back to a fighter, the fighter has the same level as the mage did. For example, if I level my mage up to level 2, my fighter, who was previously level 1, becomes level 2. I really want a system where the classes level independently of one another, is this possible without scripts?

Thanks in advance