I tested an end game DS Class and confirm that Dark Protection will only activate on Direct Weapon Strikes by Player and Foe. Unholy Strength does passively empower Dark Protection with high Physical Armor from end game Items. Cursed Armour is more effective at keeping the Player alive and Minions such as a max rank Death Knight will also benefit survival greatly. The left Skill Tree is the most powerful in terms of passive and active Skills that favor large Damage amounts dealt at far range against crowds and lone targets. The mid Skill Tree will serve to augment Damage with Minions which is very effective while the right Skill Tree requires the Player to battle up close and personal against foes. I hope this response helped with your decision making for building a powerful DS Class Build matching thy preference.