Fall on one’s sword

The literal meaning is to commit suicide by inverting one’s sword and falling upon it as disgraced Roman generals used to do after losing battles. People have been falling on their swords in this manner since time immemorial and there are references to it in the Bible, Samuel I 31:5, “And when his armour bearer saw that Saul was dead, he fell likewise upon his sword.” Oddly enough, the figurative meaning to take responsibility or blame for something is much more recent and the earliest citation appears to be from the 1980s.