the Knights Templar was active during this time and also scribed their swords with prayers, the more popular swords were ones of ornate design specially crafted for higher ranking members and Sir Knights. The lower ranking knights may have had a sword of ornate design, but wouldn't use them in battle, but kept at home instead kind of like a trophy from an outstanding deed. as far as being found in a river, this would be common of the Knights Templar if one had died while transporting Christians they would put the dead knight on a boat and set it on fire with his sword on his chest. I know this does not offer any interpretation but maybe look into the lore of the Templars?