I highly recommend to use pinterest as a tool for this kind of stuff. You can find a lot of images that can help you, but try to not look a lot on other artists stuff while doing that. I mean, do what the guys above said, look for real industry machines, jewellery, weapons etc.
In my opinion the best references for weapons, armors and this kind of stuff you can find is looking at history... armys in this case. Really, this can sound freak, but you have thousands and thousands of years of people looking for functional and cool shapes, designs etc. You're going to find really crazy things, specially helmets xD. And as I said, you can use pinterest to organize your references. Then you can try to understand what the ones that you liked works and mix one with each other and just play around.
But always remember that a weapon is a tool. You can/need to be creative, but keep in mind functionality.
Hope it helps, at least a bit. ^^