By the time she realized that, her right hand had already forcefully drawn her sword. She had used the true Yuisen. That ultimate attack that could cut down even a monotheistic angel flew straight for Knight Leader’s neck.
He was unarmed. He had nothing that even resembled a weapon and his suit was not a spiritual item.
And yet, with a tremendous noise, he grabbed Kanzaki’s sword with a single hand.
[...]
“As for those against which it has been proven... yes, it should be able to handle something on a level similar to the slashing attack wielded by the Saint of the Far East, designed to fight divinity”
[...]
Kanzaki let out a loud cry as she used a god speed sword-drawing technique. Using the idea of manipulating other teachings to counter a specific religion and cause damage to the opponent, even the angels in a monotheistic religion could be sliced in half. This was Kanzaki’s killer move.
[...]
Single Flash, Yuisen.


Toaru Majutsu no Index Vol. 17 ch.4 pt.7, vol.18 ch.5 pt.9, vol.16 ch.3 pt.1