My experience with conservation of badly corroded artifacts, especially fragile ones, is to act quickly. Once out of the ground where it has lain for so long, there is a speeding up of the deterioration process. As they dry out ...they crumble. The distilled water does two things. One, it leeches out the salt which alleviates the breaking off of what good metal what is left. Two, it is a good stable environment for it until you decide the next step.This is why cannon and anchors are left in a solution while awaiting conservation, so as to not dry out. I know this is not an artifact of that nature, but it is an artifact in need of some measure of attention. To some it may be insignifigant, but I do try to conserve all old iron that I dig, if for nothing else... to identify it and photograph it for my own records. Old knives are cool relics worthy of a little help....imo