In short, it is a small, very fast metal drone the size of a dagger that is designed purely as an offensive weapon. It's primary attack is its electromagnetic effector field which it can make narrow and intense enough to cut flesh. Here is a quote from Use of Weapons which gives a fuller flavour: “The man thrashed wildly in the centre of the room for a second, then he was a blur through the air above her, there was another colossal pulse of sound, and a ragged aperture appeared in the wall over her head, beside the window looking out to the square. The floorboards jumped and dust choked her. 'Stop!' she screamed…something thrummed past Sma's shoulder and darted down towards the men. One of the warriors roared, brandishing his sword and lunging towards the door of the inn. He managed two steps. He was still roaring when the knife missile flicked past him, field outstretched. It separated his neck from his shoulders. The roar turned to a sound like the wind, bubbling thickly through the exposed wind-pipe as his body crashed to the dust… Faster - and turning more tightly - than any bird or insect, the knife missile made an almost invisibly quick circle round most of the riders, producing an odd stuttering noise. Seven of the riders - five standing, two still mounted - collapsed into the dust, in fourteen separate pieces. Sma tried to scream at the drone, to make the missile stop, but she was still choking, and now starting to retch. The drone patted her back. 'There, there,' it said, concernedly. In the square, both of the inn-keeper's daughters slipped to the ground from the mounts they had been tied to, their bonds slashed in the same cut that had killed all seven men. The drone gave a little shudder of satisfaction. One man dropped his sword and started to run. The knife missile plunged straight through him. It curved like red light shining on a hook, and slashed across the necks of the last two dismounted riders, felling both. The mount of the final rider was rearing up in front of the missile, its fangs bared, forelegs lashing, claws exposed. The device went through its neck and straight into the face of its rider. On emerging from the resulting detonation, the machine slammed to a stop in mid-air, while the rider's headless body slid off his collapsing, thrashing animal. The knife missile spun slowly about, seemingly reviewing its few seconds' work, then it started to float back towards the window.”

Thanks guys Speedwise I suggested a combat move of 20 / 200. Mach 1 was the out of combat maximum speed that I guess would take concerted acceleration to achieve. Take your point about it being in the very small class. Fields not effectors - got it. Allowing it to use more Fray against ranged is a great idea and helps to represent its manoeuvrability.