Samurai could be mainly a frontal assault DPS where the more damage you take the more damage you can deal. With skills that add sorts of HP regen and mitigate the ammount of damage necessary to increase the damage you do. Samurai should also have a lot of DoT effects since Katanas by their nature cause wounds that bleed profusely their focus could also be crippling debilitation of the enemy such as being able to decrease an enemies resistances to being stunned and paralized by using skills that DoT while nerfing the enemy resistances. Samurai would be exclusively middle or light armor while DK could use Heavy armor but not have the Defence increase that a Paladin would or a Warrior.