A murderous child is tricked into a hand-to-hand fight to the death by the man who had him tortured

I might have gone too far obscuring this one.

Hint: this particular child is NOT the protagonist, but the whole heart of the plot is a straight shot as described above

Hint #2: the child was tricked into a fight to the death, but the fight is interrupted seconds before one of the fighters actually dies. The fight was meant to be to the death, but death is (very narrowly) avoided.

Hint #3: the other person in the hand-to-hand fight was also quite young

Hint #4: the torture of the child happens offscreen, but the fight is onscreen, and very one-sided