Pulsewave rifles are Shotguns, plain and simple. They do more damage the closer you are to the target.
in this aspect, the Cryo Launcher is actually a very weak gun compared to Sonic Antiproton Assault Rifles just because the Tholians skitter around so fast that they rarely ever stay in close range to you.
"My frozen dairy-based confectionery attracts all the males of the species to the facilities. They all agree on it's superiority. Indeed, it is superior to yours. I could teach you the finer details but that would require monetary recompense on your part." -The Milkshake Song: Vulcan Edition