“Mistempered” has three possible meanings:

• During fabrication, a steel sword is tempered, or hardened, by quenching the hot metal in cold water. These swords were mis-tempered by being quenched in the blood of their owners’ neighbors.
• To temper something can also mean to use it. These instruments of war have been misused in a lowly street brawl.
• Finally, the swords could be seen as stand-ins for their owners who are enraged, in a bad temper.