Please make it a % bonus. Also please make the Forge > Blacksmith > Armorer improvement defense boni percentage based.
I know the game isn't about realism, but it seems kinda silly to me that a forge would give an unarmored unit some defense.
I also understand it's easier to balance raw numbers.
I do not like abilities with a % bonus, because they can get out of control (warlock + evoker + item), but i think if such a bonus is used carefully it would improve the game balance.
For example lethal is too weak at the moment and even with the next patch it will be probably weak, but if lethal would increase the damage by 25 % / 25 % it would be easier to balance the weapon damage. In that case the bonus of the axeman, bruiser, spearman and swordsman abilities should be reduced to 25 % / 25 %. These traits should be available to the following paths:
Assassin: marksman (damage of power shot is increased by 25% / 25%) and swordsman
Commander: archer (damage of rain of arrows (bow ability) is increased by 25% / 25%) and bruiser
Defender: bruiser and swordsman
Mage: evoker (damage of overcharge (staff ability (next attack ignores fire, ... resistance)) is increased by 25% / 25%)
Warrior: axeman, bruiser, spearman and swordsman