toldos

After יצחק gave the berachos to Yaakov instead of Eisav, Eisav cried bitterly and said to יצחק, don't you have even one beracha that you could give me? Then יצחק blessed him saying, משמני הארץ יהיה מושבך, From the fatness of the earth shall be your dwelling.
Asks הגר"ח מוולוז'ין, how could יצחק bless Eisav with משמני הארץ when that's the beracha that he just gave Yaakov?
On the words משמני הארץ, Rashi comments that it's referring to איטליא של יון, Italy of greece.
Why over here does Rashi say that משמני הארץ is referring to a specific land, while by the beracha of Yaakov he doesn't say what it is referring to?
The gemara says (shabbos 56B) that when Shlomo Hamelech married the daughter of Pharaoh, the angel Gavriel came down and thrust a reed pole into the sea, and a sandbank formed around it. On that was built the great metropolis of Rome, the tormentor of כלל ישראל. Based on that, it turns out when יצחק gave the berachos, איטליא של יון didn't exist. Therefore, when they were given to Yaakov they didn't require explanation, for it just meant the best of the land. However, when it was given to Eisav it was for the future, so it meant איטליא של יון, as Rashi explained. So there were two different משמני הארץ. As a proof that for Eisav it was a beracha for the future, the posuk says יהיה מושבך, that it will be, sometime in the future.
Now we really need to understand this. Why does Shlomo Hamelech marrying the king's daughter cause the creation of the nemesis of כלל ישראל? And why is this alluded to now, when יצחק is giving the berachos?
The next posuk in יצחק's beracha says והיה כאשר תריד ופרקת עולו מעל צוארך, Yet it shall be when you are pained, you may remove his yoke from your neck. Rashi says what יצחק was telling him is that there is a way for you to get back the berachos. When the Jews transgress the Torah, then you can remove the yoke.
The sefer לב שלום explains that the reason Yaakov merited the berachos, was because he was involved in the study of Torah. Now if the study of Torah stops, the berachos revert back to Eisav. This is alluded to in the words הקל קול יעקב והידים ידי עשו. Why is the first קל spelled without a vav? It's telling us that when the voice of Yaakov is קל, weak, then the hands of Eisav are strong, teaching us that the only way we can overcome Eisav is with the power of Torah. Without it, all the berachos we have will go back to him.
Shlomo's marriage to the Pharaoh's daughter was the beginning of idolatry in כלל ישראל, which ultimately led to the destruction of the temple and the exile of the Jewish people at the hands of Eisav. That's why יצחק alluded to this now, forewarning us that if we go away from Torah we will lose our blessing & be in the hands of Eisav. The Torah is teaching us here that in order for us to triumph & to have the beracha that we so desperately need, we have to separate ourselves from Eisav. The only way to do that is by attaching ourselves to the Torah , committing to uphold it, & by doing so we will merit to all the berachos & the rebuilding of the temple speedily in our day!