Interesting idea, to be sure. If I had only one complaint, it would be that many weapons don't give you a whole lot of choice in how they are played--particularly the more defensive weapons. This often makes the game feel like an exercise in stalling as you wait for the "right" weapons to show up. Perhaps this could be mitigated by allowing the player to use two or three weapons at a time, though this may require you to make the enemies tougher to compensate. All in all, nice use of the theme!