I don't really know what to tell you. In my opinion, his rating was far generous than what I would give it.
It's extremely dark, looks like you just contrasted it drastically. Then yes, you simply placed dragon and an awesome smile on it. With the CSA sections you picked, I'd give it...
Detail: 1; there is none. All of the original detail has been lost by the contrasting into black. You can barely tell where something begins and ends anymore. The resemblance of a desert eagle has been lost.
Originality: 2; not many things with dragons or awesome smiles on it - then again in conjunction of functionality...who does?
Texture: 0. You didn't even make one. It's IW's default texture turned into mush.
That would leave my overall rating at 1.5 for you. Which is honest; and I also don't see anyone else giving it anything higher. You need to sit back and learn how to properly retexture a model instead of just manipulating default materials. Nothing phenomenal comes from uneducated work.