When she realized that it was a trap and turned back to face Sigma, she found a black tube with holes punched in it in several places right in front of her eyes. Just as she moved to clear it away with her blades of hair, the cylinder split, and a light more dazzling than the midsummer sun spilled out.
Sigma leapt outside as he hurled the M84 stun grenade at Assassin, noisily smashing through a window in the process. The bang and flash began immediately after, but by that time he had already started to fall. The room that Sigma and Assassin had been in was on the second floor, but Sigma skillfully righted himself in midair and landed lightly as a cat.
I can’t hope to damage a Heroic Spirit’s eyes or eardrums with a physical stun grenade, but it should distract her for a moment.

Fate/Strange Fake: Volume 4, Interlude ("The Boy Does Not Believe In God")