The final words of the Book of Haggai are:
The word of the Lord came a second time to Haggai on the twenty-fourth day of the month, “Speak to Zerub′babel, governor of Judah, saying, I am about to shake the heavens and the earth, and to overthrow the throne of kingdoms; I am about to destroy the strength of the kingdoms of the nations, and overthrow the chariots and their riders; and the horses and their riders shall go down, every one by the sword of his fellow. On that day, says the Lord of hosts, I will take you, O Zerub′babel my servant, the son of She-al′ti-el, says the Lord, and make you like a signet ring; for I have chosen you, says the Lord of hosts.”
The reference to being chosen as God's "signet ring" at least evokes a sense that the prophet predicted a restoration of royal authority approved by God (see Jeremiah 22:24). Zerubbabel was a descendant of King David and the grandson of one of Judah's last kings. Given his lineage and the powerful words of promise above, is Haggai expressing a messianic hope in Zerubbabel? (Note: I mean this in the sense of the Jewish messiah, who restores the throne of David, not the Christian sense, in which the messiah dies for the sins of mankind.)
Related questions: whether or not this is a messianic prophecy, why does it seem it was not fulfilled. Were there events in Zerubbabel's time that fulfilled the prophecy? In what sense did he become God's "signet ring?"