what Carl mentioned is absolutely true. As a Dentist, I do quite a bit of cutting on tissue so when I'm doing surgery, I want a razor sharp surgical blade. I want a nice clean cut that I can sew up neatly when I'm done.
But in a SD situation, the whole goal is for the situation to end as soon as possible, and for your attacker to run off and leave you be with minimal amount of damage to you, and a minimal amount of time engaged with the attacker.
When I make a cut on tissues, or when you cut yourself shaving - it bleeds for a long time - why? because with a fine blade there is a minimal amount of trauma, and so the body doesn't send enough of the necessary cells to stop the bleeding - so it seeps blood forever. Nervous tissue is similar - a fine cut creates little trauma so the signal sent to the brain is minimal.
With a roughened or jagged edge, the tissues are not sliced but ripped. The body interprets this trauma much more severely and reacts so - bleeding from a jagged cut stops much more quickly because your body bombards the area with the proper cells, but more importantly, the nervous system does as well, and the signal sent to the brain is immediate and much stronger.
This is why it was recommended that for a SD tool, a rougher edge is better.
But in a SD situation, the whole goal is for the situation to end as soon as possible, and for your attacker to run off and leave you be with minimal amount of damage to you, and a minimal amount of time engaged with the attacker.
When I make a cut on tissues, or when you cut yourself shaving - it bleeds for a long time - why? because with a fine blade there is a minimal amount of trauma, and so the body doesn't send enough of the necessary cells to stop the bleeding - so it seeps blood forever. Nervous tissue is similar - a fine cut creates little trauma so the signal sent to the brain is minimal.
With a roughened or jagged edge, the tissues are not sliced but ripped. The body interprets this trauma much more severely and reacts so - bleeding from a jagged cut stops much more quickly because your body bombards the area with the proper cells, but more importantly, the nervous system does as well, and the signal sent to the brain is immediate and much stronger.
This is why it was recommended that for a SD tool, a rougher edge is better.