Another sign in heaven (αλλο σημειον εν τω ουρανω). Looking back to Revelation 12,1Offenbarung 12,3Offenbarung 15,6Offenbarung 15,8-11Offenbarung 15,12-14

Great and marvellous (μεγα κα θαυμαστον). Θαυμαστος is an old verbal adjective (from θαυμαζω, to wonder) and is already in Matthew 21,42Offenbarung 16,21

Seven angels (αγγελους επτα). Accusative case in apposition with σημειον after ειδον. Cf. Revelation 8:2

Which are the last (τας εσχατας). "Seven plagues the last." As in Revelation 21:9

Is finished (ετελεσθη). Proleptic prophetic first aorist passive indicative of τελεω as in Revelation 10:7