Inspired largely by the intimidating, largely unarmored Scottish fighters that gave the British a run for their money.
Weapon and Armor Proficiency: The Guerilla Warrior is not proficient with any type of armor.
Intimidating Defense: Eschewing more protective armors, the Guerilla Warrior covers his exposed skin with tattoos and warpaint that distract and disrupt his foes in battle. He may add 1 point of his Charisma modifier, if any, to AC per level. He only gains this bonus when wearing light or no armor.
Favored Terrain: At 3rd level, the Guerilla Warrior gains the ranger's Favored Terrain class ability. At 9th and 15th level, he chooses an additional Favored Terrain. This replaces trap sense.
The biggest problem I see is that it's going to be pretty super MAD.
The build will have to most likely have a strong STR for melee, DEX to compensate for the lack of armor and CHA to build AC as they level.
Assuming they pump their CHA and DEX to stay alive with AC, they're going to have a hard time also getting solid CON and STR scores.
You have a good point. Perhaps something like this:
-Light Armor proficiency only
-Instead of the Cha mod to AC, whenever they successfully demoralize an opponent using the Intimidate skill, they a +1 dodge bonus to AC against that opponent. This bonus increases by 1 every X levels.
Initiative bonuses are something that would also be appropriate for this archetype I think, but I'm not sure how to work that in.