This altarpiece, of somewhat unusual iconography, is evidently by a Romagnol master under the influence of contemporary Emilian painters, including Innocenzo da Imola and Bagnacavallo.
The text in Saint Paul's hand is from his Epistles to the Romans (16:20), 'And the God of peace crush Satan under your feet speedily; [the grace of our Lord Jesus Christ be with you]', and was intended as a an adjuration to the viewer as well as an attribute (with his sword) of the apostle.
The picture is shown in situ in the chapel of the 'Neugebäude' at Feldsberg in a watercolour by Rudolf von Alt (Liechtenstein Collection, inv. no. GR 30).