Description
The Dark Knight dress sphere deals with status effects. For example, you can inflict doom, petrify, and poison. Also, some skills allow you to damage the enemy through some sacrifice of some sort.

How Aquired
When you enter "Bevelle-Labyrinth", there will be a fall-away wall. There will be three lifts ahead. Use the left lift first. Climb until you reach a chest with a hi-potion in it. After that, continue south, fall down, and use the north lift. You'll see a switch which will activate two pillars. Go back and take the right lift to the upper level. Now take the left lift back down. Now use the north lift, which will grant you access to a new switch. Hit the switch, go back down, and take the left lift back up. Use the lift here to ride to the pillars, where the dress sphere lies.

Ability Highlights
Ability to inflict multiple status effects, plus statusproofs make this Dress sphere very interesting. Some skills involve some sacrifice, so it's up to you to decide if that sacrifice is worth it.