As another idea:

Join those bars together and give the new bar 3 states:
physical, neutral, magical

Physical armor gets only half damage from physical attacks (warriors), magical only half damage from magical attacks (mages), neutral armor gets normal damage from both kinds (archer, rogues, etc.) or alternative neutral gets only half damage from both, but offers in general lower numbers of armor. Not sure what would be better.

Heavy armor will give you physical armor, leather/light armor neutral and mage clothing magical.