Use one Omni Light and adjust its brightness and scene placement. Change it's color to white. (or whatever color you want)
Add raytraced shadows. Choose a good ground texture. Try to get a texture without shadows. A good trick to use is use the HL2 ground textures and tile them on the plane.
Then render using default or your desired renderer. Use Catmul-rom supersampler
Models need to be lighter. Double the amount of lights you have and add exclusions onto them, one light will light up the floor and the other light will light up the weapon. The one with the weapon should be brighter than the one that lights up the floor.
Also I suggest adding a falloff effect to the weapons. Go to your materials tab and select the reflection material and select falloff then there should be a few drop down boxes, select the one that says perpendicular and change it to fresnel. You can see more about that here. Ignore what that says about applying it as an opacity mask, doing that will make the entire model transparent/translucent and will only produce the falloff effect (If I recall correctly).
Finally I suggest making the shadows stronger and making the background higher in quality, try and use 2048^2 or 4096^2 textures for the background. Also post higher resolution images, strive for 1920x1080.