Radak: The prefix Hei in "ha'Oyev" calls out to them, like "ha'Kahal Chukah Achas Lachem" (Bamidbar 15:15) and "ha'Dor Atem Re'u Devar Hashem" (Yirmeyah 2:31). Refer to 9:7:2:6.

Rashi #1: The swords of hatred are always against him, like a sharp sword.

Rashi #2: The enemy, that the swords of his hatred were forever against us, i.e. Amalek - "v'Evraso Shemarah Netzach" (Amos 1:11), [was finished off].

Rashi #3: Charavos it is an expression of Churban (destruction. The enemy was finished), an eternal destruction - "Shimemos Olam Etencha v'Arecha Lo Sashovnah" (Yechezkel 35:9).

Radak citing his father: The swords that you used to make - you will not make them again.

Radak citing Ibn Ezra: Because the cities that you destroyed were finished, and the cities that you razed, memory of them was lost, you thought that you will escape - you forgot that "Hashem always sits" [in judgment - verse 8].

Malbim: Know, you the enemy, that even though the cities that you destroyed permanently will not be rebuilt, and you do not fear lest they take vengeance against you - and the cities that you razed, no one remembers them, so you do not fear lest grandsons or other relatives take vengeance for them - there is a still a Go'el ha'Dam. This is the Go'el that never forgets (Hashem - verse 8).

Rashi: "If Edom will say, we were poor [initially, but now that we are rich from the spoils of Yerushalayim - Rashi Mal'achi 1:4], we will return to rebuild our destroyed cities - so Hashem said, they will build, and I will tear down" (Mal'achi 1:4).

Radak: Just like the name of the cities that the enemy destroyed was wiped out, and there is no remembrance of them, so the enemy will perish, and there will be no remembrance of them.

Radak #1: The pronoun is doubled (the suffix Mem in Zichram would have sufficed).

Radak #2: There is no remembrance of them, to the point that those who see them say "Hemah" (are they the cities that were built?!), in astonishment.