That’s what in the USA they call a certain spot on a baseball bat and in the UK a cricket bat when you strike the ball and there is no shock travelling down the handle. It’s the sweet spot if you will. Centre of percussion (COP) is identified on tools too, especially tools like hammers.
Today I used a hammer I bought yesterday to see how it worked. It’s a UK made hammer made by Thorex. I decided to try it but found fault with the handle which has a plastic grip over the main hammer shaft. I liked the feel and the weight and the balance of the hammer but the handle felt more rounded than oval and I felt it a little large even for my large hands.
I smoothed off any coarse bits with 150-grit abrasive paper as shown. I also roughened the hammer face a little too.
What a great tool. I think this is a keeper for £17.00.