Whose sword is the Pasuk referring to?
Rashi, Targum Onkelos and Targum Yonasan: It refers to the sword of an invading army (which the expression 'Hava'as Cherev' always implies - Rashi).
What are the implications of "N'kam B'ris"?
Rashi: It implies that there is a vengeance that is not based on the covenant, with reference to the blinding of the eyes of Tzidkiyahu.
Rashbam: It means that Hashem will avenge the B'ris that He made with you and which you abrogated. 1
Seforno: It refers to the punishment of Cherev that is mentioned in the Torah, 2 and which Hashem brought upon them 3 when, for whatever reason, the Sanhedrin did not operate. 4
Targum Onkelos and Targum Yonasan: It meanss that Hashem will take revenge from you because you nullified His Mitzvos.
Rashbam: See above, Pasuk 15.
Presumably, the Seforno interprets "Seifer ha'Beris" as Mishpatim, which contains the Mitzvos that Hashem gave Yisrael at Har Sinai, where He entered into the Bris with them.
Seforno: As occurred in the days of Malchei Yisrael, as foretold by the Navi Elisha in Melachim 2, 8:12.
Seforno: See Kesuvos, 30a.
What is thee meaning of "Vene'esaftem el Areichem"?
Rashi and Targum Yonasan: It means that they will be gathered from the fields outside into the towns, on account of the siege.
What is the connection between the pestilence and being handed over to the enemy?
Rashi and Targum Yonasan When they go out to bury the people who died in the plague of pestilence, 1 the enemy will capture them.
Seforno: Being handed over to the enemy refers to the ten tribes falling into the hands of Sancheriv, King of Ashur.
Rashi: Since it is forbidden to leave an unburied corpse in Yerushalayim overnight.
QUESTIONS ON RASHI
Rashi writes that the blinding of the eyes of Tzidkiyahu is not based on the B'ris. What does he mean by that?
Moshav Zekenim: He means that it is a plague that is not written in the Torah. 1
Moshav Zekenim: Even though the Torah writes in Ki Savo Devarim 28:28 "Yak'chah Hashem ... u've'Ivaron", that refers to a natural blindness.