Each unit has an individual minimum stat, but can be adjusted, dependent on that particular unit's stat maximum. The number of allocable Stats increase with a unit's Rank.
Armor blocks damage. Your strength - their armor = damage.
Strength is both damage and health. If strength drops to 0 the unit falls unconscious.
Willpower is spent to move further, hit harder, and perform your ability, but does not replenish.
Exertion is the amount of Willpower you can use on any given action.
Break is the amount of direct damage you can naturally do to an enemy's armor.