Bought this service from Kantuu at Unyielding Pass, though it did nothing. Verified with diagnosis tool and checked twice.
It'll allieviate but may not reduce it to a lower level
Withering cures take points off the overall total, but don't necessarily bring you down a full level. It often takes multiple times to actually come down a full "rank" of Withering.
They work, I saw a PC go from heavy withered to light through them but he had to chainchug ALOT of them. I don't think they're as potent as remove curse spells, but there is no EXP penalty.