Tirapugni & pulling punches

I was listening to a new (to me) Italian song and learned a new word! TIRAPUGNI, brass knuckles.
I'm a lover, not a fighter, so it seemed odd to me that the Italian term for something that makes punches harder/more painful sounds like something we say in English for lightening up on a hit so the other person isn't hit as badly, i.e. "pulling your punches." It almost seems like a bilingual contranym!

Is there a phrase in Italian like "pull your punches"? Or is there a different origin for the word "tirapugni"?

Edited to add link to the song! "un tirapugni d'argento sopra ad un guanto di seta..."