#4 can't be Constantius I, as he was dead by the time Maxentius issued this type. Maxentius issued the CONSERV VRB SVAE with 3 different reverse spellings for himself, Maximian Herculius and Constantine I. I seem to be able to make out an X in the obverse legend, so Constantine I is out. I believe that I can make out a faint I after the X, if so it is Maximian. In hand it might be clearer though.























