I know it is not a weapon, but I wanted to try and do completely hand drawn textures and I picked this concept art because it has a bunch of different textures and materials. Apart from drawing the textures I added a layer of grain to mimic the texture of watercolor paper. It took me about 2 days to finish it.
The concept art was made by Arthur Malagon : https://www.artstation.com/artwork/KOegQR