A small adjustment:

If the game isn't short, then forget about machines. Leadership is extremely useful for a Barbarian; Orcs aren't known for their initiative, and positive morale allows troops to move more often. Not to mention the powerful skills "aura of speed" and "battle frenzy." In some cases, you can take diplomacy and empathy, especially relevant for Krag.

The "barbarian luck" skill doesn't work! No matter how high the luck stat, the damage is always reduced by 5%, which is extremely small and won't help at all against a Warlock. There's no need to invest in any luck skills at all; it's completely unnecessary.

The ballista should be combined with fire arrows; otherwise, the damage won't be impressive.