What is the meaning of "va'Yifen Elav Hashem"?
Rashi: Hashem Himself talked to him. 1
Radak: He clothed him with strength.
Malbim: The angel was an intermediary before Hashem's word would be revealed to him, like when Yehoshua was in Yericho (Yehoshua 5:13 - 6:2). (Gid'on was worried when he realized that it was an angel (verse 22). If he spoke with Hashem Himself, why was he worried that he saw an angel? (PF) Refer to 6:17:2:1*.)
What is "b'Kochacha Zeh"?
Rashi, citing Tanchuma Shoftim 4): It is the strength of advocating for Yisrael 1 . (Refer to 6:13:2:1.)
Radak: It is the strength that Hashem put on him now (refer to 6:14:1:2), like "va'Tehi Al Yiftach Ru'ach Hashem" (11:29), "v'Yad Hashem Haysah El Eliyahu" (Melachim 1 18:46).
Malbim: It is the strength that Hashem put on him, and his claim that Hashem removed His Hashgachah; due to this, he is prepared to save them.
Mesilas Yesharim (19): Hashem loves only one who loves Yisrael.
Why did he say "ha'Lo Shelachticha"?
Radak: This strengthens the matter, like "ha'Lo Shamat Biti" (Rus 2:8), "ha'Lo Tzivisicha Chazak ve'Ematz" (Yehoshua 1:9).