Another state of matter.
Any element can be heated past its limit, into a liquid, then a gas, then plasma, etc. But if you super-heat past that, you wind up with Essense. Essense is odd in the form that it acts like a liquid unaffected by gravity. The only way to move it in this form is by reducing air pressure fowards, or increading air pressure backwards. Weaponry that uses Essense have a few problems. First; Speed, the fastest essense gun fires bullets at 400 mph, Secondly; When the bullets hit anything, it hyper-cools itself and hyper-heats the objects in millionths of a second, reducing effectiveness on living organisms, but massively increased armor penetration; Litterally melts through.