expression
incredible danger; giving a sword to a madman
Proverb meaning that giving a dangerous tool to an unstable person invites disaster. Literally 'a sword to a madman'. The term 気違い is now considered discriminatory, so the expression is sensitive and often avoided in modern usage.
彼にそんな権限を与えるのは、気違いに刃物を渡すようなものだ。
Giving him that kind of authority is like handing a sword to a madman.
この状況で彼女を一人で行かせるなんて、気違いに刃物だよ。
Letting her go alone in this situation is incredibly dangerous.
Both describe making a bad situation worse, but 気違いに刃物 specifically emphasizes giving a dangerous tool to an unstable person, while 火に油を注ぐ is about adding fuel to any kind of conflict or problem.
A traditional Japanese proverb. The exact origin is uncertain, but it likely arose from the obvious danger of arming someone who is mentally unstable. The phrase uses the now-discriminatory term 気違い (madman), which has led to its declining use.