Sold by Nazramu, a djinn you "pulled" into your world using Spectacles of Spectacle during Zaviak's Vision Quest, used only by monks.
The blindness effect on critical hits can be applies by any mainhand weapon or unarmed attack, but it doesn't work with offhand weapons.
Description[]
| “ | Rumor tells that a remote sect of monks, living in deep caverns beneath the Spine of the World, learned to fight in absolute darkness. The sound of their enemy's movement and breathing were enough for them to accurately target their blows. These bracers put their enemy on an even footing. | ” |