Hyper Velocity Rockets
qualifies as a heavy weapon. While very fast firing the rockets don't
do a lot of damage and the number supplied is small, you can easily run
out. With the power-up, much, much better, it can do a lot of damage
against a fast-moving target.
K-9 Drone (Hidden Weapon)
definitely the strangest weapon in Future Cop. When fired it sends out
a robot dog to attack the enemy. It does a lot of damage and will
follow an enemy. It will also run straight into walls trying to get to
the enemy (it's not very smart, it's only a dog). It's also of little
use against Sky Captain in later levels because it can't keep up with
him. With the power-up it fires several dogs at once.