The museum of Trebizond houses a seal with a metrical legend of special interest, documenting a Synadenos, who had for some time been in a Sicilian prison but managed to escape, and thanks the apostle Thomas for this liberation. He might be Andronikos Synadenos, the husband of Theodora Komnene, a daughter of Alexios I, who served with distinction as general and as diplomat. As a military commander he maintained order in several border regions such as Dyrrachion, Niš, Cyprus, and finally Trebizond. The legend of the seal enhances the information from his epitaph which is known from Codex Marc. gr. 574: Synadenos must have been taken prisoner as dux of Dyrrachion, either at the fights during the Second Crusade in 1147/49, or during the failed expedition to Southern Italy; it ended in 1158 by a peace treaty which included an exchange of prisoners. The seal stems from Synadenos’ last post in his military career as dux of Trapezunt (before 1179), since it was found there. A parallel piece, also published in this article, is nowadays in Dumbarton Oaks.