a metaphor for a subtle, gradual, or imperceptible way of causing harm or destruction to someone

软刀子杀人不见血，这种精神上的折磨比身体上的伤害更可怕。

underhanded or devious methods used to attack, undermine, or harm others without open confrontation

他表面上对人客气，背地里却总是使软刀子来排挤竞争对手。