What is the comparison to a Gibor?
Radak: Hashem will go out to save Yisrael like a Gibor goes out to war, without fear.
Malbim: A Gibor's strength is in his loins. He goes out to war by himself. So Hashem Himself will override the Ma'arachah via miraculous conduct.
Who is "Ish Milchamos"?
Malbim: He is not a Gibor, but he is experienced in war tactics. He himself does not fight; he arouses Kin'ah in the hearts of the soldiers to arouse them to fight. So Hashem will arrange nature and the Ma'arachah to agree with His acts against His enemies.
What Kin'ah will He arouse?
Radak: Kin'ah of Yisrael, who were subjugated in Galus for many years.
What is the significance of "Yari'a" and "Yatzri'ach"?
Radak: This is a metaphor. Victors in war scream in order to overpower their opponent. Yatzri'ach is like Yari'a, but louder.
Malbim: The Ish Milchamos blows Teru'ah of victory to strengthen his troops, and scares the enemy and softens their hearts, and causes them to scream amidst breakage.