so, somewhere on this forum is a discusiioon about leather or linen armour, and it mentions a anecdote from the crusades of a man who was struck by a cast stone from a ballista and who was realtively ok because he wore a layered gambeson of some sort (we infer its a gambeson, the account just describes it)

does anyone know where the passage is from, and even better, if they can direct me to the document

because it also describes the king of france wearing scale armour which is WIERD

Are you thinking of the story from the siege of Acre in 1189-1191 where a footsoldier was shot with a ballista or an arbalest through his hauberk and his his pourpoint but saved by something with the name of God on it which he wore around his neck? IIRC that is in the Latin Itinerarium Peregrinorum "Route of the Pilgrims" and the French History of the Holy War by Ambroise.