If you can show us a wireframe image of it, I couldn't really see the red lines in your picture you posted because it's a terrible quality of jpg (i'm assuming). Do you want the side of the blad to be flat like it is, or to curve around?
Probably starting with a flat plane and then extruding edges would be the quickest way to knock that out. What you've got there seems perfectly serviceable though. I don't understand what your concerns are about the modelling. Perhaps you could post up some wires shots.
The silhouette of the weapon is fine. I assume what you're having trouble with is getting it to not look like it's flat or beveled like you have it now. You seem to be getting confused by the lighter green material that's near the edges of the blades. Notice that on the original model that all the edges come together to a…