What is the significance of Hashem's burning Anger?
Rashi (in Sotah, 47b) Perversion of justice always brings about Hashem's anger.
Seforno: Whenever a victim cries out in anguish, Hashem has compassion on the victim and displays anger towards the oppressor.
What are the ramifications of Hashem's burning Anger?
Mechilta: Based on the Gezeirah Shavah "Vecherah Apo" "Vecharah Af Hashem" in the second Parshah of the Sh'ma, it results in a shortage of rain and Galus. 1
Oznayim la'Torah #1 (citing the Eliyahu Rabah): When R. Shimon ben Gamliel asked Yochanan Kohen Gadol why they were being killed like Mechal'lei Shabbos, Ovdei Avodah Zarah and Megalei Arayos, he replied that it was perhaps because they indulged in food and drink, and when Almanos and Yesomim came to them for help, they did nothing to alleviate their suffering - and he quoted the current Pasuk.
Oznayim la'Torah #2: The punishment of death by the sword, as the Pasuk goes on to explain. It incorporates the oppressor, the Beis-Din 2 and those who appoint the Dayanim, in keeping with the Mishnah in Avos (1:5) ''Sword comes upon the world for delaying judgment and perversion of justice'.
Having stated "Veharagti eschem", why does the Torah need to add "Vehayu Nesheichem Almanos ... "?
Rashi: To teach us that not only will their wives become widows and their sons, orphans, but, since there will be no witnesses to testify on their death, 1 their wives will be Agunos (unable to remarry) and their sons will be unable to claim their inheritance. 2
Meishech Chochmah: To teach us that they will be killed by the sword 3 - the Malchus, which will then take their money, in which case their widows will not be able to claim their Kesubah and their children will not inherit.
Why does the Torah not simply write 'Mos Tamus', like it does by other Chayvei Misos bi'Yedei Shamayim?
Ramban: Because, as opposed to other cases of Misah bi'Yedei Shamayim 1 (which is synonymous with Dever - pestilence), someone who afflicts a widow or an orphan will die by the sword or simply disappear without trace in battle. 2
See for example, Kedoshim Vayikra, 22:2 and Korach Bamidbar, 18:32 (Ramban).
Ramban: And this also explains why the Beraisa cited in Sanhedrin, 83a does not list this among the Chayvei Misah bi'Yedei Shamayim.
What is the significance of the punishment?
