Depends on what you want to change about them and why.
You could try The Amethyst Dragon's
Project Reforged: Weapons - Complete.
Or specifically
Reforged: Heavy Blades.
In any case, I also recommend Kamiryn's
Customize Character Override Hak (CCOH). It allows you to cycle through available weapons parts and colors to customize your weapon a little, among other things. It does replace the defaut crafting dialogue though, so don't use it if you care about NWN's skill-based crafting system. (I don't mean specific, module-related "bring me this and I craft you that" quests, just the regular stuff you create yourself via the radial, with "Craft Weapon" skill etc.).
EDIT: Oh yeah, sorry, I automatically assumed your question was about the first game. Was it? Always state which NWN you are referring to! :)