topic...
i think that armors could give protection against energy attacks. if i was caught in a fireball, an acid shower, a cone of cold, etc. i'd rather wear fullplate than a chain shirt.
of course, some might argue that lightning attacks should harm you more in this case, ok. make it even more complex und give penalties, too, though i personally wouldn't... there is so much unrealistic stuff in dnd, that this won't make a difference. it would just complicate things and again nerf armor.
further, i think letting medium and heavy armor increase touch ac with a small portion of their ac bonus would help, too, along with fortification (why on earth is fortification a magical effect? why do they think full plate armor was invented in the first place?).
right off my head i suggest:
armor | | touch | | resistance | | fortification |
------- | | ----------- | | ----------- | | -------------- |
light | | - | | ac bonus/2 | | - |
medium | | ac bonus/2 | | ac bonus | | %=ac bonus |
heavy | | ac bonus/2 | | ac bonus | | %=ac bonus*2 |
i'd say for these adjustments, special materials, such as mithral, count as an armor type reduction, too. thus, if you wear a mithral breast plate, you won't get any touch ac bonus and no fortification.
i hope this really makes as much sense, as it does to me right now, and that this is no total brain fart.