Torah as our shield

וַיִּשְׂטֹם עֵשָׂו אֶת יַעֲקֹב עַל הַבְּרָכָה אֲשֶׁר בֵּרְכוֹ אָבִיו (27:41) The simple pshat in the pasuk is that Eisav hated Yaakov and wanted to kill him because of the bracha that Yaakov stole from him.  Abarbanel (see Chizkuni as well) has a different twist:

אחשוב שחוזר לעשו וירצה על הברכ׳ אשר ברך אביו לעשו כי מפני שיצחק ברכו ועל חרבך תחיה והיה כאשר תריד ופרקת עלו מעל צוארך חשב עשו כי בחרבו ינקום ממנו ויפרוק עלו מעל צוארו ולכן בעבור הברכ׳ אמר ברכו אביו ממנה נתיעץ וחשב מחשבו׳ להרוג את יעקב 

Eisav hated Yaakov and wanted to kill him, says Abarbanel, because of the bracha על חרבך תחיה that Eisav received from his father. Eisav felt emboldened, and thought that at the right moment he would have his revenge.  

For now, Eisav held himself in check: 

 וַיֹּאמֶר עֵשָׂו בְּלִבּוֹ יִקְרְבוּ יְמֵי אֵבֶל אָבִי וְאַהַרְגָה אֶת יַעֲקֹב אָחִי

I do not understand R' Ben Tzion Aba Shaul's question of why Yaakov had to flee if Eisav was not going to harm him at this moment.  How did Yaakov know what Eisav was thinking and know that there was no immediate danger?  (Though see Ibn Ezra יאמר עשו בלבו – יתכן שגלה סודו לאחד מאוהביו)

Why did Eisav hold back?  Did he delay to avoid causing pain to Yitzchak, or was it a calculated strategy?  The meforshim are divided.  Ramban writes that Eisav wanted to avoid doing anything to cause suffering for his father, and therefore he figured he would wait for Yitzchak's death before killing Yaakov.  It's an amazing thing -- even as he was plotting the crime of murder, Eisav was meticulous about kibuv av!  We also see that Eisav did not understand kibuv av in the sense of accepting his father as a role model of proper behavior.  Whatever Eisav could get away with outside his father's knowledge was fair game.

Targum Yonasan sees Eisav's delay as a calculated move:

ונטר עשו שנא בליביה על יעקב אחוי על סדר בירכתא דיברכיה אבוי ואמר עשו בליביה לית אנא עביד היכמא דעבד קין דקטל ית הבל בחיי אבוי והדר אבוי ואוליד ית שת ברם מתעכב אנא עד זמן דימטון יומי אבלא דמיתת אבא ובכן אנא קטיל ית יעקב אחי ואנא משתכח קטול וירית.

I don't understand why the theoretical possibility of Yitzchak having more children bothered Eisav given that his beef was specifically with Yaakov for having stolen the brachos.  

Netziv and Kli Yakar also see Eisav here as calculating, but instead of reading יְמֵי אֵבֶל אָבִי as referring to the death of Yaakov, they understand it as referring specifically to the time of aveilus.  Netziv writes Eisav figured that Yaakov would avoid him, but when Yitzchak would die, they would come together, as all families do to bury their father and mourn.  That would provide an opportunity for him to pounce.  

Kli Yakar suggests that Eisav knew that Yaakov's Torah protected him from harm.  (Interesting that although Eisav was a rasha, he recognized this reality.)  Therefore, he figured since an aveil is prohibited from learning Torah, the period of aveilus would be his moment to strike.

R' Shteinman in Ayeles haShacher questions the assumption of this Kli Yakar.  An aveil is in fact allowed to learn Torah.  He may learn hil aveilus, he can learn other sad things, similar to what we do on 9 Av.  Yaakov wouldn't have been just sitting and doing nothing during shiva.

Many answer by distinguishing between the mitzvah of limud haTorah, which even an aveil can engage in, and the segulah of Torah affording protection, which is a din not in learning per se, but rather is a product of ameilus and deep immersion in Torah.  An aveil can learn, but cannot learn with the same amkus and the same intensity as a regular person.  

Earlier in Lech Lech the Torah describes Avraham going out to war (14:13)

 וַיִּשְׁמַע אַבְרָם כִּי נִשְׁבָּה אָחִיו וַיָּרֶק אֶת חֲנִיכָיו יְלִידֵי בֵיתוֹ שְׁמֹנָה עָשָׂר וּשְׁלֹשׁ מֵאוֹת וַיִּרְדֹּף עַד דָּן

Netziv there comments:

 בנדרים (לב,א) איכא מ״ד שהוריקן בתורה. והוא פלא, מה זו שעה לדברי תורה? אבל הענין הוא כמו שכתבתי לעיל (יב,יז) דזכות התורה היא חרב של ישראל, ובזו הזכות הגין ה׳ ולחם בשביל אברם, על כן כל שהמלחמה כבדה יש להעמיק יותר בהלכה ולשנן את החרב.

וכך עשה אברם הוריק את חניכיו בהלכה עמוקה עד שהיה קשה להם להבין והוריקו פניהם.

He goes on in the Harchev Davar to cite the gemara (Meg 3):

״וילן יהושע בלילה ההוא בתוך העמק״ (יהושע ח,יג), וא״ר יוחנן, מלמד שלן בעומקה של הלכה

Not just any learning, but specifically learning in depth, learning with intensity and effort, is what bring us victory against those who would seek to harm us.

2) R' Yisrael Najara was the chief Rabbi of Gaza in the 1500's and was the composer of K-h Ribon.  If you don't already say it, maybe at this time it would be a good idea to make sure not to skip his zemer at your table.