NICE FIND!! I know of 2 ways,, easy or time consumming (better result), The easy way you can paint it but it has to be a heavy coat, and you can use such as rustoleum catyalist paint that changes rust to steel, but first you have to clean it well, scrape or sandblast the heavy scale off. The 1 problem in this method is that depending how long the artifact was in the water the sandblasting or scraping could turn your 9 pounder into a 9 ouncer, the rusting process can still continue on the inside under the paint! The Other way (time consumming) way, an electrolysis bath which is easy to set up but timely. If you want more info drop me a line or If you find another way through other members, but untill you decide keep the artifact submerged in freshwater cause if you found it in salt water the air will be havoc on it! Ive used the electro on restoring/cleaning parts and for artifacts. Theres a aleast a 50pounder that I found in a dive, but its encrusted to rocks and one tip is broken at the shaft 38ft water, maybe thinkin its better to leave it and go back and look at it with just bubbles!