"Vayira Yaakov m'od vayeitzer lo - And Yaakov was intensely afraid and was distressed" (VaYishlach 32:7). Commenting on the seeming redundancy of the verse, Rashi quotes from the Midrash: "vayira" - lest he be killed; "vayeitzer lo" - lest he kill others. At first glance, the second concern is difficult. Since Eisav and his men were presumably coming to kill Yaakov, he would be allowed and even required to defend himself even using deadly force. Why would this "distress him"? Many commentaries on Rashi deal with this question. Mizrachi explains that concerning Eisav, Yaakov's was worried that if he killed him, Yitzchak, having been deceived as to Eisav's true nature, would curse Yaakov thinking that Yaakov had killed an innocent man. Regarding Eisav's men, Mizrachi suggests that Yaakov was concerned that he would be required to use non-deadly force (echad mei'eivarav) to defend his family if possible as mandated by the Torah and, in the heat of battle, would kill them instead.[2]
Gur Aryeh presents the possibility that Yaakov was concerned that Eisav's men were forced to join Eisav and were not intent on harming Yaakov. However, since this was unknown to Yaakov, he would have to utilize deadly force against them to protect himself. In response as to why this was a cause of distress since Yaakov would have the right to assume they were attempting to kill him, Maharal compares it to an unknowing sin, a cheit beshogeig. This approach appears to be difficult since if Yaakov would have a right to assume that they came to harm him, he would be totally justified in eliminating the threat. Why should this be considered a cheit beshogieg? Rav Yehoshua Hartman in his footnotes to Gur Aryeh explains that concerning killing, the resultant taking of an innocent life even if done in accordance with halachic directives still requires kappara.[3]
Nachalas Yaakov offers a third approach. The Gemara (Berachos 7a) quotes the verse in MIshlei (17:26) "Gam anosh latazadik lo tov" which it interprets to mean that punishing is not ideal for a righteous one to do. Here too, Yaakov, even if justified in defending himself from Eisav, did not wish to have to do so.
Apparently Mizrachi and Gur Aryeh who do not offer Nachalas Yaakov's approach do not view the act of killing the wicked in self-defense as being in any way objectionable. Perhaps this debate is reflected in the debate between R' Eliezer and the Chachamim concerning whether weaponry is considered an ornament with respect to carrying on Shabbos (see Shabbos 63a). R' Eliezer, based on a verse in Tehillim, maintains that it is viewed as an ornament to which the Sages reply that it is a disgrace (genai), and this is why all forms of war and weaponry will be nullified in the Days of Mashiach. R' Eliezer seems to view killing the enemy in war time as something positive as any other mitzvah would be viewed. Those who would harm and destroy the Jewish people should be destroyed; this is a source of pride not shame.[4] Chachamim seem to hold otherwise. True, destroying the enemies of Israel is a mitzvah, but it is not a source of pride; we would rather not have to do so. My Rebbe, Rav Hershel Schachter shlit"a often taught, "War is a mitzvah, but like maror not matza!">[5]
Perhaps we can offer an additional explanation to Yaakov's distress. The commentaries note that Shmuel HaKatan was the one chosen to author the blessing of VeLamanshinim in the Amida since he taught in Pirkei Avos (4:19), "Binfol oyivcha al tismach - When your enemy falls do not rejoice." Consequently, he would write this blessing not with a sense of personal vengeance against the wicked for harm caused to him but would concentrate on the destruction of the wicked as a means of eliminating those who were preventing Hashem's master-plan for the world from coming to fruition. In other words, he would write the blessing l'sheim shamayim and not for personal, vindictive reasons. Based on this idea, Rav A. Y. HaKohen Kook zt"l explained why once Shmuel HaKatan, as sh'liach tzbur, paused in reciting the blessing (Berachos 28b). Could the author himself have temporarily forgotten his own blessing?! Rather, he was then feeling personal anger toward the wicked; he therefore waited until he could recite the blessing with concentration totally for the sake of Heaven.
Rashi (32:22) quotes from the Midrash that the absence of Dina from the procession bowing to Eisav indicates that Yaakov placed her in a box and locked it so that Eisav should not see her and desire to marry her. Because of this, Yaakov was punished by having to undergo the anguish of her being attacked later by Shechem. Rav C. Y. Goldwicht zt"l, founding Rosh HaYeshiva of Yeshivat Kerem B'Yavneh, questioned why Yaakov was not justified in not wanting to risk his daughter marrying a rasha. Whereas she might have transformed him for the good, there was certainly a risk that he might transform her toward evil! Rav Goldwicht taught that the answer lies in the extra phrase, "and he locked it". By doing so and not sufficing with just closing the box, Yaakov Avinu acted reflecting a bit of personal enmity toward Eisav and was not acting totally l'sheim shamayim. Since HKB"H is very meticulous with tzaddikim, Yaakov was punished for this lapse.
Based on this idea, perhaps that is the reason for Yaakov's distress. He was afraid that even if he would kill Eisav in self defense, there would be some personal enmity injected into the act, and it would not be done solely l'sheim shamayim.
The Jewish people are commanded by the Nosein HaTorah to engage in a broad range of commandments in His service. Some are intuitive, even second nature; others challenge us to submit to the Divine will even against our nature. Following the directives of the Torah even if against popular societal notions or norms is always inherently morally correct. Nevertheless, the sensitivity that our Sages have expressed regarding the loss of any innocent life or even the need to take a life reflects a holistic, moral value system filled with nuance conveyed to us by our Creator.
[1] Many more sources are relevant to this broad topic. Here, we quote some of them emphasizing the commentaries on our parasha. Also see Megilla (16a).
[2] See Mizrachi for a distinction discussed and debated at length by the acharonim that to defend oneself, there is no need to attempt to disable the attacker; deadly force can always be used. See Rav Rosen, Techumin (10:pp. 76 ff.).
[3] This perhaps is relevant to the taking of civilian lives in war time. Even though this is justified if necessary to achieve the military directives (see Gur Aryeh to 34:13), it might still require kappara. V'tzarich iyun.
[4] See Malbim to Tehillim (149:9) who expresses a similar thought. Also compare Sha'ul HaMelech's misguided argumentation in sparing King Agag and the cattle of Amaleik and Chazal's rebuke of his logic (Yoma 22b).
[5] I hope I have presented his view accurately. However, see Igros Moshe (Orach Chaim 4:81) where Rav Moshe Feinstein zt"l explains that in the view of the Chachamim, the disgrace is not the need to kill the enemy but the fact that our sins caused the murderous enemy to arise in the first place.