I believe your sages need to go back to the Word of G-d and the Table of Nations in Genesis Chapters 10-11. The Edomites are clearly shown as Semitic, and the Romans, Greeks, and other Indo-Europeans are Japhethites.
Rabbi Elie Munk, zt’l, briefly discusses the subject in his commentary, The Call of The Torah:
“In Talmudic sources and in Midrashic literature, the names Esav- Edom are often identified with Rome...Later, when Rome adopted Christianity, the same appelation was conferred upon the whole of the Christian world. Flavius Josephus [famous Jewish general and historian] records that Tz’fo, a grandson of Esav, was the founder of Rome, which eventually became the center of Christianity. Since then, it has become traditional to consider the Christians as representative of Esav’s off- spring and the Jews as descendants of Yaakov. The antagonism between Jacob and Esav is thus symbolic of that between Rome and Jerusalem....” (I, p. 337)
It would seem, then, that the parsha could be giving us an insight into the Jewish relationship with Christianity. Yaakov’s prayer, “Rescue me from my brother, from Esav,” is a siman, a sign, for us. We must be wary of the “friendliness” of Esav no less than of his hostility.
http://www.ou.org/torah/savannah/5758/vayishlach58.htm