Why does it say "k'Gibor Efrayim"?
Radak: All of Efrayim will be like a Gibor in war, like it says above "v'Hayu k'Giborim" (5).
Malbim: The 10 tribes are included in Efrayim. They will be aroused with strength to fight Hashem's war.
Why will they rejoice?
Radak: They will rejoice in their victory over their enemies.
What is the comparison to wine?
Radak, Targum Yonasan: [They will rejoice] like one who drinks wine. Also "Ki Chamudos Atah" (Daniel 9:23) is like Ish Chamudos, "Letz ha'Yayin" (Mishlei 20:1) is like Letz ha'Shoseh Yayin.
Malbim: Simchah will be aroused in their hearts like the Simchah aroused via drinking wine.
Why will their children see and rejoice?
Radak: The minors and youths, who generally do not fight, they will see that their fathers defeat their enemies in war.
Malbim: The children of that generation will not need war. They will see the salvation that I saved their fathers, and rejoice constantly over the past salvation, and also have a new Simchah in Hashem constantly via new miracles that He will do for them, and the Divine appearance that will increase constantly.
