"I don't understand the composition, but it's true that you can nullify fatal attacks. That's your defense! In that case…!!"

[...]

"In Norse mythology, there are a lot of stories about putting gemstones on the hilt of the sword. It seemed that it could become some sort of talisman, and it had the effect of healing the damage sustained in battle… But for me who is not well-versed in that, I can't do anything other than dodging all fatal attacks."

Toaru Majutsu no Index New Testament vol.4 main.31