Quicksword

Irene (the Organization's former No. 3) is the creator of this technique. It was her signature move, earning her the title "Quicksword Irene."

Usage
The Quicksword is performed by channeling all of one's yoki into one arm, essentially letting that arm awaken. In essence, the user's arm goes berserk with full yoma power while the rest of the body strives with all of its might to control it. The end result is a barrage of sword swings with such great velocity that it is impossible to see with the naked eye. Irene does not even appear to draw her sword when using this technique.

Using the technique requires a tremendous amount of concentration to contain the yoki within the arm alone, as the natural instrinct is to release yoki throughout the entire body. Irene's superb spirit is well-suited for the technique. Her mastery of the technique is such that she does not even show the slightest hint of exertion while executing the move, even for prolonged periods of time.

The Quicksword was first seen against two yoma when Irene rallied with Priscilla, Sophia, and Noel in a yoma hive in order to commence the mission to kill Teresa.

During the fight between Ophelia and Clare, Irene intervened and saved Clare. Later, Irene taught Clare the technique so that she could remain formidable despite losing her dominant arm. At the end of the training, Irene explained that the technique was not compatible with Clare. The Quicksword required perfect calm, and though Clare outwardly portrayed such, her heart was a whirlpool of passion. As such, Irene gave Clare her remaining arm so that Clare could perform the technique at half of Irene's speed and power.

Quicksword and Windcutter
After the first encounter with Awakened Beings in Pieta, Flora was quick to notice the similarity between her own technique, the Windcutter, and Clare's Quicksword. Both techniques work with a split-second's high acceleration of the sword, delivering an incredible number of consecutive attacks.

After the fall of Pieta, the Seven Ghosts had to hide their auras, meaning Clare could no longer use the Quicksword freely as it required yoki. Given the similarity of the Quicksword and the Windcutter, as well as in honor of Flora, she took it upon herself to learn the Windcutter.