Victrix, I think the ridges are there not to cut the flesh, like in modern arrowheads, because they seem to have been made dull, even when new. I think they are there to increase the diameter of the head to maximize wound entry size, at the same time to increase the weight of the head marginally so that the arrow has mass and can travel far enough.
I like what you say about the armour-piercing properties, but do not agree (yet) that the ridges could act as stabilizing fins. But then, I have been known to err, big time!
Johan
