Weeds with thick, pubescent (hairy) leaves create a boundary layer of air. Water-based sprays just bead up and roll off. Because 522 is oil-based with a specific gravity lower than water, it drags the droplet through the hairs and explodes on contact.
If you can provide the manufacturer's name or the industry it's used in, I can immediately generate the accurate technical data sheet, safety content, or product description. opticut 522