Cleopatra, catching but the least noise of this, dies instantly; I have seen her die twenty times upon far poorer moment: I do think there is mettle in death, which commits some loving act upon her, she hath such a celerity in dying.
There are no more uses of "mettle" in the play.
Show samples from other sources
The Trials are a test of my mettle.
Sabaa Tahir -- An Ember in the Ashes
But I will say, too, that for every man who showed no fear or hesitance, there were three or four or five others whose mettle was as unashamedly wan and mortal as yours or mine.