1784 Royal Spanish Document signed by King Carlos 3rd

I purchased a 1782 gold 1/2 Escudo about 2 years ago and I was the only bidder on a auction (got it at the price of melt for the gold. The description stated it came with a Old Spanish Document and low and behold when it arrived it was a beautiful Royal document. I had it checked by a expert at the museum and verified its authenticity. It concerns the induction of a member into the Order of Santiago and is signed by the King as well as member members and Governors reigning during that time. So I constructed a Acid/PVC free protector for it and placed it between 2 pieces of glass and it resides in a dark place. As you can see from the 3rd and 4th Pics it has a beautiful water mark in the paper.