The topic started by @susangrosseyauthor reminded me of a question I had when reading the memoirs of Auguste Petiet ("Mémoires du général Auguste Petiet, hussard de l'empire", edited by Nicole Gotteri, S.P.M., Paris 1996, page 343).
During the battle of Gebora, the author, then at the rank of a captain, I believe, was wounded in the head during a cavalry fight, by a sabre cut. After a rather desperate struggle he's brought out of the danger zone:
I call my hussars of the 10th and the former children of Lassalle support me and lead me away from the battlefield. I met the marshal who asked me if the wound I had received in the head was from a gunshot. On learning that it was a sabre wound, he exclaimed: "Ah! that's so much better! [Ah! Tant mieux!]" - This "so much better" showed me his interest and I was touched by it. Can somebody explain to me why Soult is so relieved on hearing it's "only" a sabre wound? Were gun wounds generally considered more dangerous (maybe due to infection risks)? Or is this rather some idea specific to Soult (who had suffered a rather bad leg wound in Genoa)?
I have data on the severity, location and cause of wounds suffered by 4,200 French officers in the Peninsula, about 40% of all combat injuries for this cohort. It shows that sabre injuries were indeed the least likely to prove fatal; cannon wounds were nine times more lethal, and musket wounds four times more deadly. So Soult's relief is both justified, and understandable.
The data has been extracted from Officiers de Napoléon tués ou blessés pendant la guerre d'Espagne (1808-1814) (de Blas and Campos) , which Jorge Planas Campos most generously sent me in digital form. It's a monumental effort, and a gold mine!
I recall the survey of battle damage to allied aircraft in WW2. Although riddled with holes, surprisingly the cockpit and engine areas showed very little damage. Aircraft shot in these areas never made it back to be surveyed of course.
Perhaps skull-crushing penetrative sabre wounds were so often fatal that anyone presenting themselves at a dressing station was always lightly wounded?
I'd add to Hans-Karl's description of debris left in the musket ball wound that cloth from the injured man's garments would be driven into the wound (and unclean garments at that) and the ball might shatter a bone leaving bone fragments to fester.
Surgeon Hugues Ravaton in his book Chirurgie d’armée argues that sword cuts, so long as you survive the initial blow, tend to be more superficial and thus easy to stitch up.
"Cuts that hit the skull with force and violence are very severe, even if the wound to the skin is light. Those that form great wounds and which hew through the skull are infinitely less. The reasons for this difference are that in the first case the skull might have been shaken and that there might be an effusion of blood on the brain which is often ignored for quite some time. While in the second case the shock on the brain is less to fear and that you quickly see what you need to do. This is why penetrating wounds to the skull are less severe than those that deeply affect the bones."
https://hemamisfits.com/2020/04/02/very-perilous-a-sword-wounds-compendium-by-the-surgeon-ravaton/
Larrey commented in one of his memoir volumes, if I remember correctly, that slash wounds heal much better and faster than gunshot wounds. The soldiers, who were often wounded themselves or witnessed the healing process of their comrades, probably knew this too.