Revese Gravity Weapons, or RGWs, are ranged weapons that utilise gravity to cause bodily harm. They are unusual pieces of technology that are rarely encountered even amongst the more technologically adept races in the galaxy. This is because the process of developing them is dangerous and unstable. They are commonly called Gravguns. To this date the only forces to make extensive use of these weapons are an alien race called the Derkallen.
Contrary to the image that these weapons call to mind, RGWs do not reverse gravity in a given area or on a specific target. Each weapon has a core made up of super dense matter, usually of rare origin. This core produces a strong gravitational field. Internal mechanisms within the weapons isolate this field in order to keep it from effecting the outside environment. When fired the gravitational field is channeled down the barrel of the gun and projected outward in a straight line. Special technology within the barrel changes reverses the direction of the gravitional force. This results in the guns firing a potent, fast moving, and invisible line of gravitational force. The shot from the gun are very strong and will instantly plow through any matter in front of their trajectory. Imperial Guardsmen who have fought forces utilising RGWs have given them the nickname "Hole-Punchers". This is because the wounds that result from the weapons leave a distinctive and well defined hole in the bodies of their victims.
As stated above, RGWs are incredibly rare weapons. This is mostly because of the technology that goes in to making them and the fact that the weapons manipulate a complicated force like gravity in a weapon. The inner mechanisms are complicated, and every detail of the weapons must be perfect. Otherwise the weapons may not work or could backfire with catastrophic results. The most extreme example of these backfires was when an Imperial researcher trying to test a RGW he had made created a singularity that leveled a city block. Some Eldar Craftworlds have RGWs. these are usually tech that was recovered on crone worlds or taken just before the Fall. Modern Eldar do not have the know how to manufacture these weapons. Some Tau research teams have taken to researching Reverse Gravity Weapons, but so far the weapons produced by the Tau have been even less reliable than Imperial Plasma weaponry. The one notable faction that make extensive use of these weapons is the Xenos known as the Derkallen.
RGWs have a number of advantages in combat that make them good weapons. For starters RGWs are very good at penetrating defences. forcefields and other forms of shielding are not designed to have any effect on gravity. This means that all traditional forms of shielding are entirely useless against RGWs. RGWs are also highly affective against armor, punching clean through most forms of armor. an important aspect of the weapon is distance, because this determines the killing force of the weapon. At a certain distance the force is constant regardless of defence. So if a piece of armor or a shield is not capable of completely stopping the attack, then the force upon the wearer is no different than if they were naked. If the armor holds the weapon will usually still leave a dent and will often knock the target down. For these reasons RGWs are also good at penetrating cover. The last major advantage to Reverse Gravity Weapons is that they are stealthy. What they fire is an invisible force and most RGWs make no sound when fired, meaning that a well executed sneak attack with the weapon can be pulled off without giving away the weilders position. All of these factors make RGWs very effective tools for assasination.
As impressive as RGWs are, they do have faults. The first of which is mentioned above, that being the consequences of improperly made RGWs. After all, The Reverse Gravity Weapons use power Gravitational forces that are very difficult to control. Things that may happen due to malfuntion include: the gun itself producing strong gravityand attracting matter to itself, a sudden increase in gravity in the area around the weapon, a decrease in gravity in the area surrounding the weapon, loss of gravity, gravity reversing causeing people to fall into the sky, and in the worse case scenario generating a smallscale singularity. Another major weakness to these weapons is range. The force a shot from these weapons have is dependent on the distance between the weapon and it's intended target. This means that the weapn loses killing potential the farther away the intended target is. This makes almost all RGWs close to mid range weapons at best. It is possible to increase the killing distance of RGWs, but this means increasing the force of the shots. For reasons still inknown to many, the act of increasing a weapons power and thus it's range is tied in to the size of the weapon itself. Just as a bigger planet has stronger gravitational pull, a larger RGW has more killing force and thus more range. This means two things. First, a sniper style RGW can not exist, and second, all RGWs that have any killing potential at substantial range are heavy weapons.