Perhaps it could be considered a very short excerpt from the ΜΕΓΑΣ ΠΑΡΑΚΛΗΤΙΚΟΣ ΚΑΝΩΝ, if the words underneath were visible : Ἔτι δεόμεθα ὑπὲρ τοῦ διαφυλαχθῆναι τὴν ἁγίαν Ἐκκλησίαν καὶ τὴν πόλιν ταύτην καὶ πᾶσαν πόλιν καὶ χώραν ἀπὸ ὀργῆς, λοιμοῦ, λιμοῦ, σεισμοῦ, καταποντισμοῦ, πυρός, μαχαίρας, ἐπιδρομῆς ἀλλοφύλων, ἐμφυλίου πολέμου καὶ αἰφνιδίου θανάτου, ὑπὲρ τοῦ ἵλεων, εὐμενῆ καὶ εὐδιάλλακτον γενέσθαι τὸν ἀγαθὸν καὶ φιλάνθρωπον Θεὸν ἡμῶν, ὑπὲρ τοῦ ἀποστρέψαι καί διασκεδάσαι πᾶσαν ὀργὴν καὶ νόσον τὴν καθ' ἡμῶν κινουμένην καὶ ῥύσασθαι ἡμᾶς ἐκ τῆς ἐπικειμένης δικαίας αὐτοῦ ἀπειλῆς καὶ ἐλεῆσαι ἡμᾶς. Κύριε, ἐλέησον. (3)
On the other hand, there are really "bloody? hemp ropes/cords" criss-crossed, on the inside of the window at the centre of the cross, as shawnee noted. Might it be a medieval invented term for this "holy hemp rope" [although it could be more correctly rendered as ΘΕΟΝΗΜΑ]? Perhaps Rafael could provide a bigger image for a possible further help.