Just as a note,I've never seen "Blind opponent" described as "sand in the eyes". Usually it's using the second hand to gouge.
I was going by the description of the SE on RQ6 p.145: "
On a critical the defender briefly blinds his opponent by throwing sand, reflecting sunlight off his shield, or some other tactic which briefly interferes with the attacker’s vision." Considering that it only blinds them for 1d3 turns[1], I'd expect an eye gouge to be something more severe than just a Blind Opponent SE, although I don't see any other SEs (offensive or defensive) that seem like a solid fit, either.
[1] For those unfamiliar with RQ6, an RQ6 "turn" is shorter than a "round", with most PCs potentially having 2-3 turns per 5-second round (although they get fewer if they parry or take other reactive actions).