This is (should be) the Weapon Description Pack for all weapons included as of version 0.2120. Simply extract the folders and replace the one in vector-thrust/Objects with the new one. Information may not be historically accurate to preserve gameplay features. I spent the last three hours on this and by the end I was so tired I didn't bother checking, so if you find anything weird let me know (tomorrow)
If we have this installed via desura will it do it automatically or do you have to do this manually?
You need to manually rewrite the Weapons folder.