Center of Percussion
From SwordWiki
The "Center of Percussion", or "Blade Node" is one of the harmonic balance nodes in a sword, the other existing usually somewhere within the grip (the "hilt node"). This point is the part of the blade that, when striking a target, will generate the least vibration and oscillation in the sword. It's debatable whether there is much of an advantage or disadvantage for having this point closer or further from the tip. However, it's useful to know where it is located, since this is considered the "sweet spot" of the blade. Cutting through targets will generally be easier with this part of the blade since it will cause the least deflection. It also will cause the least wear and tear on the hilt due to vibration.
The easiest way to find the Center of Percussion is to lightly hit the side of the blade, near the center, with your palm. The part of the blade that appears not to move while the rest is oscillating is the CoP. Alternately, and perhaps more safely, you can hold the sword inverted (point down) and hit the side of the pommel with your palm to also induce oscillation to test it.
The standard way to measure this is from the base of the blade, where it meets the guard, though some manufacturers measure it from the quillions if they're forward-swept, to achieve a smaller number. For purposes of this site, we prefer to standardize on the former, though some cases of the latter probably may be found in our pages where we've taken the numbers from advertisements and catalogs.
See also: Harmonic Balance
