1)
What is "ba'Yamim ha'Hemah"?
1.
Radak: It is when the enemy comes. I will put in their hearts to leave a remnant of you.
2)
It already said above (4:27, 5:10) that the enemy will not finish off Yisrael. Why is this repeated?
1.
Malbim: Here it mentions their property. After the Churban, their captors will keep them for slaves with all their possessions, as if they are flock kept for shearing. They find favor [in the captors' eyes] due to their value, and they not finish them off.