My son borrowed a dozen precious swords from the RAF for his wedding sword party. The sword party stood outside the church in a light rain shower but not all the guys ensured the swords were thoroughly dry when they were sheathed. Before he left on his honeymoon the next day, he entrusted one of his RAF buddies to return the swords to the stores. Unbelievably, his friend forgot about the swords in his car boot for two weeks! When my son returned, he found them all covered in a thick layer of aggressive rust! It took almost 2 days of hard graft to return them to their previously pristine state. I am sure he had other things in his mind!