Originally meant literal defeat by killing, often used in historical or fantasy contexts. In the epic tale, the vanquished knights were put to the sword.
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Metaphoric Usage
Now often used metaphorically to describe complete defeat without actual violence. In the debate, her arguments put his to the sword.
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Not Literal
Even though it sounds violent, it's usually not about physical harm in modern use. The CEO's decision put competitors’ plans to the sword.