@ciku-karugi I use overlays of grunge and scratch maps along with maps based on ambient occlusion to isolate the crevices and corners. Check out the Sci-fi Helmet Shader course, https://cgcookie.com/course/shading-the-sci-fi-helmet. That’s were I learned the most.
I think your knife looks good. I reccommend you add an HDRi texture to the environment so it will have interesting reflections, bevel modifier to smooth the corners slightly, up the reflection on the blade and also add a bump map to the handle. I just used a noise texture with the scale set to 500 or so to give my handle a rough rubber look.
