"What hand could have held the knife that did my father to his death?"
He held both his hands high, the one holding the knife.
He still held the knife close enough to use it should she move the wrong way.
He turned to take the hand holding the knife in his hands.
"What if he simply held the knife in his other hand?"
This time he held a knife in his left hand.
They can hold a knife with their left hand, and do it very well.
But it was the left hand that held the knife.
She moved round, feeling under the wall with one hand, holding the knife in the other.
Suddenly she could not hold the knife to clean it.