Mystic Eyes Killers

A magical construct capable of suppressing the power of Mystic Eyes.
Since Mystic Eyes are a power derived from the oculus, Mystic Eyes Killers are commonly made into glasses. The glasses Touko wore are also Mystic Eyes Killers.
The protagonist of Tsukihime, Tohno Shiki, acquired Mystic Eyes Killers crafted by Touko from someone. They relieved him of the unbearable sight of Death, and allowed him to live normally again.
This also reflected just how self-abusive Ryougi Shiki was, declining the Mystic Eyes Killers. No… it was more an episode that reflected her heart of clear water.
As a side note, Touko poured an obscene amount of money into constructing Ryougi Shiki’s Mystic Eyes Killers, but Shiki shoved them back saying “Why should I do it to please you?”
The reason Shiki declined the Mystic Eyes Killer was the same as when she refused to wear the uniform of Reien Girls Academy.

Garden of sinners Pamphlet: Kara no Kyoukai Settings Glossary