While there have already been mentions of grav weapons, this is a field that could be very nasty. For example, a grav mine. It can be emplaced on any surface. So, it could be buried like any other mine in the ground, or it could be placed on a wall or ceiling in a building along with the floor. The size of the mine could vary from a field say a square meter in size and up. The minimum size would depend on how small you can build a grav plate.
The mine has sufficient power to run the detection / initiation system for weeks to months and in full operation as a mine for a few minutes. The amount of gravity it produces is on the order of +/- 1 to 10 G and this can be set to vary in operation.
So, these mines would work (but not limited to) something like this.
You place a conventional minefield of these and they are set off by pressure or other sensing that a person has entered the field of operation. The mine generates - 8G and throws the person activating it 30 meters in the air then generates +8G slamming the person into the ground. The person falls back on the mine and it repeats the operation ad infinitum until it runs out of power. I'd say no amount of personal armor would save you from this repeated beating at 8G that goes on for say 5 to 10 minutes.
A similar field is set and a vehicle runs over one or more of the mines. They activate variously between -10 and +10 G causing the vehicle to whiplash violently due to the varied gravity as it is torn apart by it. The crew is likewise turned to mush by the violent gravity variations.
You place these in a room in a building on the floor and ceiling. Activation is by contact. The target (victim?) steps on the floor mine and it generates say -5 G tossing the person into the ceiling mine that activates (as the floor mine deactivates due to loss of contact) and generates another -5G throwing them into the floor mine that activates... This goes on for say 5 minutes when the mines run out of power.
Or you set one on an outside wall of a building on say the 10th floor. It activates when someone enters the room it is in. It generates 6G of force and the person is pulled to it, then crashes through the wall or a window, and finds themselves no in freefall outside the building with 10 stories between them and the ground.
Ship crews could use the ship's grav plate system in much the same way. Turn it off, get the baddies floating, turn it on to max and slam them to the deck. Turn it off...
Another variant would be a grav "claymore" mine. It has the same effect, a large number of directed projectiles but fired by a grav plate generating the necessary acceleration. Totally silent in operation.