For the most part, armor and helmets are the same. But two of the helmets (Volcanic Demo Helm and Divine Veil) provide bonuses that the corresponding armor does not provide. So why not extend this concept to the entire game? Helmets can be ability-based gear while armor is defense-based gear. That is, reduce the defense on helmets and increase the defense on armor, and generally allow helmets to have higher ability bonuses. Collectively, the defense on any given set could remain the same.

Advantages:
- More variety in equipment options. People more likely to mix sets.
- More variety in items. The difference between any given helmet and armor could be more than "eh, whatever I felt like making at the time"
- Ability to hit the odd-numbered bonus levels. The way most stuff in the game works, it gets a low bonus at 3* and 4*, and then that bonus ups to medium at 5*. So the only options are +2 (low, low) and +4 (med, med). By splitting up the helmet and armor, it's a lot easier to hit +1, +3, and +5.
- Devs have more freedom in buffing or nerfing gear.

-Demonstration of a possible Wolver-line nerf that probably wouldn't anger people too badly-

2* and 3* gear: Armor provides no sword bonus, helm provides low sword bonus
4* gear: Armor provides no sword bonus, helm provides medium sword bonus
5* gear: Armor provides low sword bonus, helm provides medium sword bonus

Disadvantages:
- Not all armor has abilities. Perhaps concentrate the status resistance in the helmets?
- Added pressure to give helmet and armor different ability bonuses, making it harder to hit +2 and +4 on a set.
- Not sure if increasing defense on one and decreasing defense on another would screw with tier-scaling.