Deirdre's Mystic Weapon is the Whirlwind Crossbow. She had to earn her weapon during her quest of worth in Tir Na Nog, Deirdre had to learn to be unselfish, especially because she had always looked upon Angus and Rohan with disdain. This meant that she had to be willing to sacrifice her life, so that the other Knights could continue in their quest. As a Mystic Knight, she summons her white and silver Mystic Armor by shouting "Air Above Me!".
Designation: Mystic Knight of Air
Mystic Weapon: Whirlwind Crossbow
Deirdre is an intensely independent woman, who happens to be the Princess of Kells. Her indignant air makes her seem haughty and stubborn, yet she is also capable of great selflessness and tenderness. Her attributes range across the spectrum, she is as far away from the misconception of a princess being a 'damsel in distress.' She is a skilled swords expert, as well as an expert harpist. Deirdre has an intense desire to learn, and expand her horizons by becoming the most able ruler she can possibly be. Deirdre refuses to let any barrier stand between her and victory, and this determination is what led her to joining the pilgrimage to Tir Na Nog with Angus, Rohan, and Ivar.