Muscle vs. Armor: Blunt Impact

A weapon doesn’t have to cut or penetrate to be effective. A deed of arms done by the seneschal of Hainault in 1402 or 1403 gives one example:

And they came to fight with axes very fiercely. And taking a deceptive step away from his opponent, the seneschal brought his axe around and struck him on the hinge of bascinet and carried him to earth thoroughly stunned. And my lord the seneschal went before the scaffolds of the judges and asked him if he had satisfied them. And during this time the count of Bennevent did not say a word.

A deed of arms at Noseroy in 1519 provides another. During the fighting with two handed swords there were “many basinets and armets driven in.” A deeply dented helmet can be driven into the wearer’s skull, and even if the helmet isn’t dented enough force can be transmitted through the padding to stun or worse. Fighting with a two handed sword the count de Bussy “gave such a stroke to (Jean) de Falletans, on the armet, that he kneeled in the sand.” The prince d’Oranges “gave a stroke of the sword on the crest of the armet of Phillipe de Falletans so that he had to take three steps back from the barrier and was unable to fight any more that day.”

In addition to the risk of concussion, the inside of some helmets could be driven into the wearer's face by a sufficiently violent blow. Henry, the first duke of Lancaster, wrote in his Seyntz Medicines that" a man who frequents these tournamets has a nose damaged more than any other part". At Noseroy, Claude de Vienne was wounded in the head “to the effusion of blood” by a single handed sword stroke.

Powerful blows that fail to penetrate can also bruise the flesh beneath. According to the Chronicle of the Monk of St. Denis, partway through the jousts at St. Inglevert in 1390 Boucicaut and Reginald de Roye were so bruised "that they had to keep to their beds for nine days"

Broken arms and collarbones were common enough in jousting that Ponç de Menaguerra's late 15th century jousting rules included them explicitly in the scoring system. Suero de Quiñones had his right hand dislocated twice during the Passo Honroso of 1434.

Likewise, a non penetrating edge blow to the gauntlet can deliver enough force to injure the hand within it. The small plates of gauntlet fingers don’t spread the force of a blow over a very large area, and finger plates and scales don’t seem to have had any padding beyond that provided by the leathers they were riveted to.

Flexible mail can absorb some of the force of a blow where it drapes away from the body, as the weapon looses energy moving the hanging mail, but otherwise does little to spread the force of a blow. It essentially makes a sword act on the body like a narrow steel club, with a similar ability to inflict blunt trauma. Places where bones are close to the surface are particularly vulnerable.