Hi Anneke~ Yes, that is a strange one and not in the dictionary. A prong is one of those long, pointed extensions on the end of a fork, whether a small one for eating or a large one for pitching hay. Also prongs or points on a deer's antlers. The sense of unprong here as it is being used is of unhooking claws from you, or fingers as is stated.

I think of those garden implements for cultivating that have curved under tines for loosening up the soil. They aren't exactly prongs, but that is how it is used here. Usually prongs would be used to poke or spear, but here they are used to grab on and hook like a cat catching a mouse.

I would say if a literal translation of this coined word doesn't work, translate it as if it said "Unhook worry from you . . . ."