We know they practice their skills with the OP often. We know they are skilled with destruction. We know they're anti-Aiel, in the sense that they have the Aiel endurance and courage, but a totally perverted honor and no morality.

They're like the worst parts of the damane and a twisting of the Aiel combined. I think they're a quietly developed resource that goes a long way to explain RJ's quote that the Light is at a serious disadvantage. Add in the women (who Isam seems unfamiliar with), and you may even have mixed circles of these evil Aiel causing massive destruction.

And I think the sight of them, and the horror of the destruction they bring will be catalysts for the Aiel to realize how wrong violence is. Aviendha has struggled with this in her thoughts. She has worried about her desire for violence before. I think they presage a confrontation with these abominations, and the realization that the violence the Aiel embody is a double edged sword. That this violence needs to be renounced, and that is only way to gain ji. The Aiel will feel great toh for the existence of these creatures. I think the Aiel saying about spitting in Sightblinder's eye, and the choice of "eye blinders" as the name for this Aiel clan is foreshadowing that these Red Viels will meet their counterparts, and the consequences will be huge.