The Holy Martyr Onesimus (Onisius) lived in Palestine. He was beheaded with the sword for confessing faith in Christ.
Troparion — Tone 4
Your holy martyrs Conan and Onesimus, O Lord, / Through their sufferings have received incorruptible crowns from You, our God. / For having Your strength, they laid low their adversaries, / And shattered the powerless boldness of demons. / Through their intercessions, save our souls!