Breaker Gorgon

Self Seal: Temple of Darkness.
Self-imposed mystic eye killers.
Rider's blindfold, which seals her too-powerful mystic eyes within a boundary field (world).
Shirou's lewd dream in the Sakura route was the result of his being captured by this temple of darkness. Within that world, he had his blood and semen sucked under false pretenses.
In any case, as you can see, the blindfold is there for a good reason.
“What, did you think I was wearing something like this just for fun?”

Fate/side material: Fate Encyclopedia