For physical characters I generally would level STR, VIT (can't remember if its Vitality or Stamina in FoE..), DEX to generally be able to act before enemies and finish them before they attack. Mastering Fighter and Bruiser will net you the skills that'll let you beat each of them easily enough. Attacks that ignore their defense will generally deal the most damage to them, but backstab isn't so bad either if you can land a debuff that lets you use it since it also has no cooldown and SP efficient to make up for the conditional use.