天てん下かの宝ほう刀とう

expression, noun

last resort; trump card

Idiomatic expression meaning a final, decisive resource kept in reserve. A non-standard variant of 伝家の宝刀, often used humorously or emphatically.

See also: 伝家の宝刀

• 彼かれは最さい後ごの手しゅ段だんとして天てん下かの宝ほう刀とうを抜ぬいた。

  He drew his trump card as a last resort.

• 交こう渉しょうが難なん航こうしたとき、社しゃ長ちょうは天てん下かの宝ほう刀とうを使つかった。

  When negotiations stalled, the president used his ultimate trump card.