Discriminating, a.
Marking a difference; distinguishing. -- Dis*crim"i*na`ting*ly, adv. And finds with keen discriminating sight, Black's not so black; -- nor white so very white. Canning.
Shades of meaning
Fernald has no entry of its own for discriminating; he lists it under astute.
He lists it without comment; the entries above explain its neighbors.