Those are push-blades. If a piece of sharpened toothstick can kill people, then why not some sharpened pieces of concealable thin metal?
Indeed, these are assassination weapons. They aren't meant for the open battlefield, they are meant for sneaking up behind someone in a dark alley. The intended victim isn't supposed to know a thing until they are perforated. One minute they see a cute girl walk by, the next they are bleeding out in a dumpster.
