Rhomphalias are a thing of beauty. When I first won one in a tournament, I didn't think much of it. I knew that the falx was a good weapon, and this was just a falx on a stick, right?
Wrong. The falx hits like a truck, but this thing hits like a truck on a stick. I've been using it on horseback, and I'm hitting for about 200 damage per swing on average. More importantly, it can reach farther than most polearms used by any faction's foot soldiers, meaning with a little maneuvering you can pick off infantry with near impunity. Enemy horseman aren't safe either, possibly even less so; at full speed, I can hit for about 300 or more, meaning it doesn't matter if I hit the horse or the rider, I've ruined someone's day.
It's also really, really fun to use. I had trouble landing hits at first due to the timing and distance, but once it clicked I basically had a couched lance that hits from the side. The curved blade has a way of wrapping around certain shields to hit enemies who aren't blocking properly, and once I somehow managed to kill two enemies in the same swing. It's satisfying as hell when you get it right.
Having said that, tt's not a perfect weapon. That long reach actually works against you in some circumstances. More than a few enemies have gotten away due to the blade catching on a boulder or tree trunk, and you get the same result if you try to use it anywhere near allies. I haven't tried using it in an urban environment, but I expect it wouldn't go so well.
In short, the rhomphalia probably isn't the sort of weapon you want to use in a siege battle or dense forest, but in an open field it is a devastating and extremely satisfying weapon.