Answer:
The pronoun "it" refers to "the blow" the speaker spoke of delivering to someone.
Below is an evidence from the poem that supports my answer:
When I saw your head bow, I knew I had beaten you.
You shed no tear—not near me—but held your neck
Bare for the blow I had been too frightened
Ever to deliver, even in words. And now,
In spite of me, plummeting it came.
Frozen we both waited for its fall.
Explanation:
From the speaker's tone, we can infer that the speaker speaks of delivering a "blow" (like a punch) to an opponent. The stage looks like a "boxing" stage.
So, the narrator recounts that in spite of been frightened to deliver such blow, yet it still came with a heavy force.
"The Last Word" is a poem written by a poet known as Peter Davison.
