The figure on this lamp can be identified by the double-plumed helmet, a characteristic of the god Mars. Furthermore the spearhead he is depicted carrying could be a martiobarbulus, which would translate as ‘Barbs of Mars’. They were lead-weighted darts stabilised with a feathered and infantrymen would carry five of them in the hollow of their shields. They were originally introduced in the late 3rd century under Diocletian’s reforms to the army, used by the newly established Legiones Palatinae.
This particular lamp can be categorised as a variant of Bussière form D X 1. This lamp category was characterised by ovolo decoration to the shoulders, a continuous tongue and dot pattern. The ovolo design seen here is altered slightly, hence the variation.