The Weapon and His Wielder — Zoe Cannon

Eamon's quest to steal the enchanted sword went perfectly... right up until the sword betrayed him to the enemy. Now he has nothing to look forward to but a lifetime in a prison cell with no one but that traitorous jerk of a weapon to talk to. But the sword is facing an even worse fate... unless they can figure out how to work together.This short story is 8200 words long. It is also available in the short story collection Love Is Strange.