That doesn't make sense. Short swords are a specific, more rare type of sword. The most common type of sword would be a longsword.
On Nirn you can make someone kill their friends by shooting red light out of your hands and into their brain. Does that make sense?
Anyway, it's the only reason I can come up with for the presence of both shortswords (all the so-called "swords" we've seen so far) and the http://2.bp.blogspot.com/-lpfVWKVTw1A/TZTu2w3cP5I/AAAAAAAAAfI/hRysmYN9vw8/s1600/Skyrim_Cavern.jpg
Of course, if it turns out that all swords are simply "swords," but some were by nature longer or shorter, I would accept that, too. And who knows? Maybe they just haven't gotten around to properly naming everything?