I was just photographing this follis of Constantine the Great and thought it worth putting forward. I think that the Mars is well done down to the way the cloak hangs behind him and the portrait of Constantine is quite pleasing too. I really like the way in which a single line of engraving is used to convey the eyebrow. It isn't a rare variety but the type always seem quite popular.
Follis of Constantine the Great
Obv:-- CONSTANTINVS P F AVG, Laureate, cuirassed bust right
Rev:--. MARTI CONSERVATORI. Mars helmeted, in military dress, spread cloak, standing, right, holding reversed spear, left hand leaning on shield
Minted in Trier (B S / PTR). A.D. 315-316
Reference:-- RIC VII Trier 82 (rated Scarce)

Regards,
Martin