Why not having shortsword being able to aim everywhere, instead of just 45 degrees up and down?
Shortsword suck so much anyway, that you might as well make them aim everywhere.
If you are afraid of shortsword being to alike spears, don't worry, there is still range.
Mayby, you could have a zelda II mechanic with shortswords (as it later came in Ducktales and Shovel knight (exelent game).
Once you damage the mob, you knock yourself up so you can jump further to next mob (or platform).
The part where you are knocking yourself up would only work when the shortsword is angled right down (or close at least).
The reason why I am stating such obvious things is because the "jump buff" should ONLY work at a downward angle, or else you would knock your self away from enemy when you are attack normally (right in front), and that would make the shortswords well, kinda moronic...