Ah! Correct me if I'm wrong here: What you are saying is that in the future this skin would essentially take place in, the bits of "rubbish" essentially lying about that he would have to work with would be scrapped Mech armors (in a unified story-line) from, for example, a totaled Evangelion, pieces of Spike's ship from Cowboy bebop, etc.
If I have this correct, might I suggest making it look a bit less cohesive then. If you want your art to tell that story, I suggest you make the different parts look as though they have been indeed patch-worked together, perhaps by using less of a unified color theme, or giving each limb a different art direction or feel in such a way that it comes across as "this is the leg from Voltron"/"This back piece is from Gundam"/ etc etc.
As stands, it gives that feeling across when it comes to the weapons, but mecha are also known to have mismatched arms commonly in order to give weapon diversity to the pilots.
(This is, of course, nothing more than an interpretation and suggestion, meant to give insight and perhaps some artistic inspiration to better relay the vision. I always feel the story should be conveyed through the piece itself, and I only want to help you if that was the intent. I hope I did not offend in any way, you have my upmost respect and admiration with your art.)