Xaser Weapons
A marked improvement on laser weapons, xasers use a higher frequency beam that pushes into the ultraviolet range for more damage, greater accuracy, and increased range. The power requirements of these weapons means their ammo capacity is lower than that of laser weapons, and their somewhat delicate construction means they can't be used to bash enemies.
If you want to be physically correct, you should not say that UV radiation allows for increased range, it's actually the reverse. Atmosphere of Earth is not universally transparent, for wavelengths shorter than about 5cm, it becomes rather opaque, and transparent only in a few windows of transparency.
Visible spectrum is located on the top of such window, and in the UV range trasparency rapidly decreases. For the Xrays and gamma radiation atmosphere is very opaque: at the sea level, 1km thick atmosphere layer provides shielding equal to 20cm thick steel plate. That's why nuclear explosions cause giant fireballs and powerful shockwaves instead of short and invisible gamma ray flashes: atmospheric absorption of gamma rays, which causes them to heat the air right into the plasma state.
PS: Of course, UV will be more effective than optical radiation when delivering the actual damage, since more energy will directly go into breaking molecular bonds, and less into simple heating.