Swords are cool. That's why heroes prefer them. But for some authors, it seems that a sword with a plain, straight blade, a curved katana or scimitar, or some other exotically functional real blade like the wavy kris is still not quite cool enough. They need to invent their own special blade. So screw functionality and ergonomy! They will design swords with the weirdest shape possible, as long as it looks cool, or at least unique. The odd shape won't have any practical purpose other than looking special, when it isn't outright Awesome but Impractical… not that it will prevent the wielder from fighting perfectly with it.