Here is a quote from St. Augustine's commentary on Psalm 2 that might be of some assistance
7. "Ask of Me, and I shall give Thee the nations for Thine inheritance" (ver. 8 ). This has at once a temporal sense with reference to the Manhood which He took on Himself, who offered up Himself as a Sacrifice in the stead of all sacrifices, who also maketh intercession for us; so that the words, "ask of Me," may be referred to all this temporal dispensation, which has been instituted for mankind, namely, that the "nations" should be joined to the Name of Christ, and so be redeemed from death, and possessed by God. "I shall give Thee the nations for Thine inheritance," which so possess them for their salvation, and to bear unto Thee spiritual fruit. "And the uttermost parts of the earth for Thy possession." The same repeated, "The uttermost parts of the earth," is put for "the nations;" but more clearly, that we might understand all the nations. And "Thy possession" stands for "Thine inheritance."
8. "Thou shalt rule them with a rod of iron," with inflexible justice, and "Thou shall break them like a potter's vessel" (ver. 9); that is,"Thou shalt break" in them earthly lusts, and the filthy doings of the old man, and whatsoever hath been derived and inured from the sinful clay. "And now understand, ye kings"(ver. 10). "And now;" that is, being now renewed, your covering of clay worn out, that is, the carnal vessels of error which belong to your past life, "now understand," ye who now are "kings;" that is, able now to govern all that is servile and brutish in you, able now too to fight, not as "they who beat the air, but chasteningyour bodies, and bringing them into subjection." "Be instructed, all ye who judge the earth." This again is a repetition; "Be instructed" is instead of "understand; and" ye who judge the earth instead of ye kings.For He signifies the spiritual by "those who judge the earth." For whatsoever we judge, is below us; and whatsoever is below the spiritual man, is with good reason called "the earth;" because it is defiled with earthly corruption.