Disarm rarely works but when it does it is quite useful. Monsters with weapons hit harder than those without them. Disarm might allow you to throw the weapon from the monsters hands and grab it for your own keeping. Last but not least shadowknights get meditate at level 14. This is an important skill when it comes to spellcasting as it will drastically reduce downtime while waiting for mana.
Shadowknight spells are probably the most varied among hybrids.
Rangers get nice outdoor spells with a bit of healing thrown in. Paladins get buffing and healing spells with some undead direct damage spells thrown in for good measure. Shadowknights get a great mixture of different spells. The majority of these spells revolve around undead, summoning undead, finding undead and destroying undead. However it doesn't stop there.