Section 1
The color scheme for the Dark Paladins is really very, very simple. It only uses a few colors. First, undercoat with Chaos Black. When that drys, paint the entire model with Midnight Blue. Take Mitheril Silver and paint the shin-guards, stopping underneath the knees. Also paint the exhaust ports on the Power Packs and the eagle emblem on the chest, and the right shoulder pad. Next, take Scab Red and paint the knees, bolters and, if the model is a squad leader or special weapons character, paint the left shoulder pad. Any chain swords should also be red, with Mitheril Silver for the chain parts. Any visible flesh should be painted with Elf Flesh.
The Color Meanings
The Midnight Blue represents the Dark Paladins love of sneak attacks. Their dark armor helps them blend in at night. The Mitheril Silver represents the Emperor's holy light. The Scab Red represents the Emperor's blood and the blood of the Space Marines' enemies.
Section 2
The Dark Paladins were created because of a lack of defense in the farther sectors of the galaxy. They bring the Emperor's swift justice to the heretics of the galaxy, making sure the Emperor's wrath is swift and merciless.