Currently you can buy some throwing darts in the starter shop that have zero weight (same as arrows and bolts) But all the darts that you can buy IG (To my knowlege) weight like 5lbs per 50 darts, making a dart throwing rogue kinda hard to play.
The daggers do 1d4 dmg, and i doubt they would become overpowered if made any lighter. So i suguest having the gnome merchants sell the same daggers, as there are in the OOC starter shop.
There are a few ways to acquire these after the start area already, though I'm not sure adding more would be so bad.