I have the "Spin Doctor" Campy lockring/square taper bottom bracket tool which, as you note, does take a 1/2" square drive and also has external hex flats that fit a 21 mm socket or box wrench. It's actually made by Lifu and has been very satisfactory.

BTW, the Park Campy lockring/bb tool (BBT-5/FR-11) has hex flats that takes a 1" socket so nothing very unusual there.