“your mighty scepter.” Ps. 110:2 is addressed to the one at Yahweh’s right hand, as we see in the phrase, “Yahweh will stretch forth your mighty scepter,” with the “your” being God’s “right-hand man,” the Messiah. The first stanza in Psalm 110:2 would have been spoken by the psalmist, while the second stanza would be spoken by Yahweh (or direct prophecy from Yahweh to the psalmist). Psalm 110:3 and 110:4 continue with the address to the Messiah and thus continue to use the second person words, “you,” and “your.”
“from Zion.” The Messiah will rule the earth from Jerusalem on Mount Zion. Psalm 110:2 is a prophecy of the future, something we can see from the fact that the Messiah, who is Jesus Christ, never ruled at all in his first life on earth, and certainly not from Zion (the permanent residence and place of rulership of the Roman governor during the ministry of Jesus was at Caesarea, not Jerusalem). However, when Jesus comes back from heaven to earth and fights the Battle of Armageddon and conquers the earth, then he, the king over the earth, will rule from Jerusalem.