The Fantastic Element System

Make a super annoying boss that switches to a random resist/weak combination every 5 minutes or so. The combinations would be the same as usual: Fire and Ice are mutually weak, Lightning > Water, Light and Dark are mutually weak I think? All that's left would be to settle the combinations for Poison and what Water would have an advantage over. Anyway, said boss would only use elemental attacks of the element it's currently resistant to so players can tell which element it's currently weak to, whenever it isn't using non-elemental ones.

Or perhaps, make weapons that are really difficult to obtain (drops from a major boss at a low rate, obtained from a really long and annoying quest chain, forged by Blacksmith with rare materials, etc.) but have slight elemental properties attached to them. There would be no such weapons for any class with elemental attacks except for Paladin and Aran, but they will have their charges nerfed to reduce their advantage (since they would benefit from it too)...or just make such Swords and Pole Arms unequippable by Paladins and Aran.

The first idea is not worth it, because it just adds annoyance to the fight rather that strategy. I support the 2nd idea more, though. Still not fond of the idea that having the right element for your class will allow you to hit for massive damage, because it causes disparity among the rest of the classes. Also, what happens to those that paid an arm and a leg for their "non-elemental" weapons?

Have an idea. Maybe if you can tack on an elemental crystal to your weapon and it'd work like a buff (at least an hour or longer) it'd be more feasible, since the whole party can just stick on an elemental crystal for whatever elemental weakness the boss fight demands. Will probably be a craftable item, and will be fairly inexpensive to make so everyone can get a bunch. Reasoning for the crystal only infusing an element for an hour is that the power in the elemental crystal eventually runs out. A bit like an elemental battery.