A live weapon is a downright liability ... it's all too apt to get qualms of conscience!
stood up and walked to the packing cases the Hovans had left. All but one contained the synthetic food product to which he had grown accustomed in his five years of captivity. The other box, rather small, contained a shredded vegetable which served him as a poor substitute for chewing tobacco. Purple when growing, the leaves of this vegetable were blue-black when cured, making his frequent expectorations look like ink.
"Filthy damn stuff!" he grunted, stuffing several handfuls in an empty overall pocket.
He shuffled down to the brook and tested its temperature with a hand. Finding it rather cold, he decided against taking a bath. Instead, he spat into it and watched meditatively as the spot of black was carried downstream. "I wonder what they turned me loose for," he monologued.
Careful to avoid the spot where the Weapon appeared to have gone, he returned to the food supply and ate. By then it was getting dark, and he bedded down for the night on some thick grass under a tree.
A sentient killing machine malfunctions and is left behind during an interplanetary war. The machine survives the war, and outlives the empires fighting it. It is inherited by the next empire to come along, but it still malfunctions: it insists on good reasons for killing, rather than just following orders. So the empire gives the weapon a sample of its latest enemy to learn to hate: a farmer from Tennessee.
An amusing story, with the most sympathetic character being the killing machine.