No hammer needed for breaking a glass .Raúl Hernández VergaraTools, for almost everything, has been invented, often tools with the same shape but different size, yes, cause when it comes to tools ans its uses, size mostly does matters.
Have a look at the knifes in the image above, they all can cut in their own particular way, according to the use we give'em. They are all not sharpen though, the red third one's not, cause it's designed to cut vegetables and some salads stuff, it's very effective in those matters, but some people prefer sharpen ones to any kitchen job, meat or salad job, doesn't matter, it's a matter of preference I guess.