1)
What was the Ru'ach Hashem?
1.
Radak, from Targum Yonasan: It was a spirit of strength, from Hashem.
2)
Why did Yiftach pass Gil'ad to go to Eretz Amon? Amon was in Gil'ad!
1.
Radak (10:17): Bnei Yisrael gathered at Mitzpah to fight them, and Amon returned to their land. This is why Yiftach sent messengers to Eretz Bnei Amon!
2.
Malbim: This was Chachmah, to pass Gil'ad by the side, via Mitzpah, to Amon. It was easy to capture Amon and strike the cities severely while the king and his camp were in Gil'ad; this humbled them and forced them to return to protect their cities.
3)
What is the meaning of "Avar Bnei Amon"?
1.
Rashi: He went to Bnei Amon.
