I have found several galleries on DeviantArt covering fictional weapons, two that could be very useful are:

EdonGuraziu

PeterKu

This image from the gallery of MukkelKatz, shows that in the future well known hand weapons may change.

And finally this image, which shows that a company well known for one thing could be doing something else well less known.

These are just examples which can be used for inspiration/props if need be, though of course it should be noted that the first two named people do retain copyright over the images (And the first one has worked for the film industry.) And of course you can search the recommended images and collections for more.

Graham