In the current d&d player's handbook it displays a weapon known as a hand-crossbow. theyr'e extra-light crossbows that can be duel-wielded but only do 1d4 damage. I have messed around on the neverwinter toolset and managed to turn staves into one handed items. Is there any way you could do this to a light crossbow, give it a weight reduction, and perhaps change it's damage? (The last part I havn't figured out how to do, but I imagine you could just give it a damage reduction of 2 or something if you couldn't change the base damage.) Thus creating a one-handed crossbow? I guess it'd be kind of hard work, but it'd be fun to see some gun-slingers wandering around in lower...

Hand-crossbows are super-rad, but this isn't doable without some manner of hak.

I should point out as well that one-handed staves are available as a base item already- They are wizard's staves.

Light crossbows != hand crossbows.