Sufficiently powerful magic swords can overwhelm their owners and take control of their bodies.
So when the fighter we’d hired with a king’s ransom in the tavern drew the sword we’d lent him and growled “This one will do” in Razorwind’s cold steel voice, we knew we had our party leader back.
“This time, can you save a healing spell for my handler?” the sword asked our cleric. “The money you keep paying and taking back from them can buy a potion or two.”
The cleric whispered “Certainly, sir.” and Razorwind pulled back from his neck.
And we marched on.