We've gotten a lot of great weapon qualities that I hadn't seen before. I love deadly.
What about a riff on older editions of D&D and a little something to make combat feel a bit more like the source material?
Slow and fast weapons might be as simple as an add or penalty to initiative--say a three? You might take a page from the crossbow mechanics have slow weapons require an action between attacks for the wielder to recover whereas a fast d4 four weapon might give you a free second attack.
Just something to add a little more strategy to weapon choice, where a dagger is not necessarily always a bad weapon and a two handed sword is not always necessarily the best.