Wow, David, this is a bit more complicated than I thought...and I failed machine shop 101....so basically my target was the screws holding the arms of guard to pommel..I presume a threaded screw into a drilled hole.
Mostly I can just see the illustrations in books, so I cant really examine the components, just see the screws externally.
Great information on the earlier presence of the screw in the Mediterranean out of wood, I imagine the principle was used early in many engineering functions.
I agree that pointed screws sticking through armour would be a problem, reminds me of being in the attic with roofing nails sticking through the roof! ouch!
All the best,
Jim