What is the significance of "v'Shilachti"?
Malbim: This explains "Hineni Alayich" (22) ? I will send plague outside.
Why will there be "Dam b'Chutzoseha"?
Malbim: There will be war between man and his brother.
What is the meaning of "b'Cherev Aleha mi'Saviv"?
Radak: [The enemy] will come against it with a sword.
What is the connection of "v'Niflal Chalal b'Sochah" and "b'Cherev Aleha mi'Saviv"?
Rashi: Since they will see the sword around outside, the city residents will fall. They will be sure that they will be killed inside.
Malbim: After people die inside, the enemy's sword will come from outside. They will realize that the sword came due to murder inside - "v'Yad'u Ki Ani Hashem"!
What is the root of "v'Niflal"?
Rashi: This is like "Lo Filalti" (Bereishis 48:11) ? I did not expect, and "v'Oyveinu Felilim" (Devarim 32:31).
Radak: This is like v'Nafal, just the last letter of the root is doubled.