This is Saint David of Thessalonica, also known as David the Dendrite": the only full-sized saint who was not a martyr. He is seated in a kind of nest in a tree. Wikipedia: David the Dendrite (? - 540), also known as David the tree-dweller and David of Thessalonika, is a patron saint of Thessaloniki and a renowned holy fool. Originally from Mesopotamia, David became a monk at the Monastery of Saints Merkourios and Theodore outside Thessaloniki. Famed for his sound advice, he was hounded by crowds seeking words of wisdom and prayer. Wishing a quiet, contemplative life, David fled to the seclusion of an almond tree, where he lived for three years. He left the tree to petition the Byzantine emperor Justinian the Great in Constantinople to send soldiers to defend Thessaloniki from attack. David died in 540 as his ship was en route to Macedonia.
He alone - amongst the people represented here - was neither warrior nor martyr.