A Dragon Knight can shapeshift to dragon form with a Dragon Morph Stone. You obtain a stone after conquering Laiken and taking control of the Battle Tower on Sentinel Island with some help from Sassan.
Dragon armor can be equipped while in dragon form, providing dragons with various bonuses, including extra dragon skill points, hitpoints, mana, offense, or defense. A dragon can equip five pieces of armor, made from four different types of materials: chainmail, plate, crystal, and bone.
You must be in dragon form to access the dragon armor and dragon skill tabs.