Neonchameleon
Legend
It has been touched on a couple of times already, but worth re-stating - I think the most significant omission in D&D is weapon reach. When I first started D&D many, many years ago lighter weapons were 'intuitively' much faster. But a few years later when watching or having pretend duels with re-enactment guys (and given that these are not real fights, not real weapons yadayada) reach was THE most significant thing.
The guy that had reach dominated the duel. Swords vs daggers? Spears or halberds vs swords? It was only when you got to absurd lengths like Pike (which I believe are expressly for formation fighting?) that it might fall down.
This. I can think of one case where a shorter weapon drove out a longer one. That was smallsword vs rapier, and chiefly because the rapier was so long the rapier wielder had no leverage when the smallsword wielder used his blade to bind the rapier - the rapiers having extended to such lengths to beat shorter rapiers. (There have probably been others).
Reach matters. And because reach matters, daggers are amongst the slowest weapons out there. You might be able to twirl a dagger faster than a scimitar. But that's not weapon speed. Weapon speed is about who hits first. You need to get your hand within four inches of my chest to hit. With the scimitar, I need to get my fist within about two and a half feet of your shoulder. Or arm. Or head. And as for speed to change direction, you rotate your hand through ninety degrees and (assuming a 6" blade), the tip will have moved about 10". Due to a blade that's almost three foot long, rolling my wrist will move my blade more than four foot - or a cut that was coming for your right shoulder is now coming for your waist on your left hand side or your right thigh through a simple flick of the wrist in the same time it takes you to move your point those ten inches. And because of the weight of the pommel and blades not being that heavy this isn't too hard for someone with skill and practice.
Length is a speed multiplier. Larger longer weapons are faster where it counts. They also have more leverage and momentum (although aren't anything like as heavy as in D&D) so they cut deeper.
(And yes, pikes are for formation fighting).