I don't know if it is really relevant but in Book 1 of the Bane-Triology there is a part where the sword master explains to Bane one of the bigger advantages of dual bladed weapons. I don't know the exact wording but he said that dual bladed weapons are kind of exotic and most people don't have the necessary experience to defend against it. Against a single opponent the second blade is useless but it confuses unexperienced opponents because they are sometimes distracted by the second blade because it looks like there was more than one blade the can harm someone even if it can't. Like I said I don't have the exact wording in my head but there were a couple of pages for that kind of weapon and its combat application.