Glossiness(specularsharpness in toolbag?) defines how sharp(mirror like) or diffuse(matte) the reflection is, adjust the slider or load a gloss map(in your spec alpha?) to control glossiness.
specular are reflection are exactly the same thing. for metal like that you want a low sharpness medium reflectivity material. if its getting too bright you need to darken your diffuse. post your maps and perhaps we can offer some advice.