Light, Medium, Heavy Armor.

[Soukyuu]

I agree with the OP, heavy armor should have low ele res to offset the high phys def. They could also scale the resistance down, so that if you somehow manage to get over 100 res it will mean you will get healed instead, like in some FF before. Ofcourse that has to be made nearly impossible to reach, or have to sacrifice other resistances to reach it. Maybe even with negative resistance values, so you get an item that adds 10% to fire resist but also gives you -20% ice resist (or whatever the opposite of fire in this game is.. wind?)

It doesn't hit hard at all IMO, naked Ifrit runs for example.

Depends. Shadowsear, for example, hits pretty hard.