What do sharp points in a horse's bit speak of? The horse may not push into the rider's hand. It must not lean on him. What do vertically upright disks in ancient Greek bits speak of? The horse may not clench or grind its teeth. What do little chains attached to the bit's center joint address? It does the horse good to play with the tongue.
All three points are as valid today as they were in ancient Greece.
Modern sports riding adds a curious variation to the old Greek idea of the snaffle. It shuts down movements of jaw and tongue, disregarding the reciprocity of balance and well-being with the liberation of jaw and tongue. Time for some riders to do their homework.
The bit Xenophon describes, in other words, makes perfect sense. Even if its rough and pointed interpretation with the horse's progressive domestication today is no longer necessary. The real question is this bit's direction and impact. Does it work on the jaw or the corner of the mouth? Does it close or open the poll? How does it assist elevation?
Of course, - there is this other question: Why is it better to use a bit properly than to ride without. And, what is proper?