Doctor Jones pulls the cutlass free! Now he owns it, he knows several rather interesting things about it. First, he owns the cutlass, and will continue to own it until somebody else clasps their hand around its hilt. Two, so long as he owns the sword- he doesn't have to hold it, nor even be carrying the weapon, he knows the value of anything he looks at, and where to sell it for most profit, and he can breathe underwater as well. Three, if he brandishes the cutlass over his head, large deposits of gold will appear to glow in his vision.
Four, the cutlass is a gift, and something is watching the Doctor and his use of the weapon. If they feel it is misused, it will be reclaimed.