This week you should be starting to put the polish into your weapon concept art. It should have a clean silhouette that you can use as a mask for any finishing effects like gradient lighting. Start thinking about presentation. Here are two examples.
The first image has blueprint-style images and a photo texture of some paper in the bg. It also has nice lettering and a strong sense of compositional balance.
The second image is more loose in rendering style but again has a nice balance in terms of image placement and the use of gradients over a simple rough painted texture in the bg.
There's a lot of leeway in the presentation of this piece. Be sure to follow your hand-in parameters very carefully. Watch naming conventions, file sizes and compression guidelines.
Any questions, just ask.