[put] {sb} to the sword

to use a sword in order to murder or execute someone

The idiom "put someone to the sword" has its origins in medieval warfare and historical contexts. It has been used to describe the act of taking the life of an enemy, prisoner, or adversary in a deadly confrontation.

After the battle, the victorious army put the captured enemy soldiers to the sword.
In the heat of the rebellion, the insurgents put the king's supporters to the sword.
The brutal conqueror ordered his troops to put the entire village to the sword as an act of retribution.
In the epic fantasy novel, the hero vowed to put the evil sorcerer to the sword to save the kingdom.
In a fierce political debate, the candidate figuratively promised to put his opponent's arguments to the sword with his compelling rhetoric.