As it was said, the Hashashins' name came from herbs. They usually consumed a certain herb, one particularly known for its mind-numbing effect, before carrying out their jobs.
Jaber loathed that herb.
To that very day, he could still remember the terrifying sight of the Hashashins as they ambushed his village out of the blue. Bloodshot, wide, and unfocused eyes, broad sneers, loud laughs of ecstasy as they slayed people left or right, and the joy palpable on their faces every time they were hit or shot, as if they liked it.
In that state of trance, they claim to be able to see more clearly, to be able to move freely, and to not feel pain at all.
It was their euphoria.
From Jaber's point of view, they were nothing but a swarm of mad men swaying around drunkenly. Their sight alone was terrifying enough to force a village to surrender. He had seen it firsthand.