Life Drain is not extra damage, but instead is a way for the attacker to restore his or her hit points and fatigue by damaging an enemy. Once damage has been calculated (if the target is a living unit), the attacker with life drain:

• Increases its hit points with damage / 2
• Reduces its fatigue by damage x 2

Weapons with partial life drain are less potent, and only the first 5 points of damage dealt are treated as drain. The remainder are considered normal damage only. Life Drain cannot increase a unit’s hit points above 150% of its maximum hit points +10. Lifeless units only take 25% damage (after Protection).