What is "b'Tzel Cheshbon"?
Rashi: It is tall; it has shade.
Radak: It is the protection of Cheshbon - its residents were strong, and it was very fortified.
Radak citing Targum Yonasan: Due to hearing [about] the residents of Cheshbon. 1
Malbim: When fleers came to seek protection in the fortified city Cheshbon
I.e. This explains verse 24, why Mo'av was afraid. (PF)
Why does it say "Amdu mi'Ko'ach Nasim"?
Rashi: The fleers stopped to rest in the shade, for they had no more strength to flee.
Radak: Those who fled other cities of Mo'av stopped [in Cheshbon, hoping to be protected there].
Radak citing his father: Those who fled from the strength of their enemies, they stood in the shade (protection) of Cheshbon.
Radak citing Targum Yonasan: The weak soldiers fled.
Malbim: The enemy came to there with great strength against the fleers; due to this, they ceased to flee.
What are the fire and flames referring to?
Radak: This was in olden days, when Sichon devoured Mo'av. (Because it used to be so strong, they thought that it will be shelter now.) Refer to Bamidbar 21:28:2:1.
Refer to Bamidbar 21:28:2:2.
Abarvenel: [They could not escape to Cheshbon, because] enemies came from Cheshbon and plundered the fleers and took them captive.
Why does it say "Yatza" (masculine)? "Esh" is feminine!
Radak: Sometimes "Esh" is masculine, e.g. "Esh Lo Nufach" (Iyov 20:26).
What is "mi'Bein Sichon"?
Rashi: From the city Sichon. This is like "Ben 1 Reuven" (Yehoshua 15:6; it is the name of a city).
Rashi equates this to Ben, even though here it says Bein, with a Tzeirei and a Yud. (PF)
What is "Pe'as Mo'av"?
Radak: Until the corner; nothing remained.
Radak: [They killed] the great people of Mo'av.
Abarvenel: The remnant of Mo'av. Malbim: This is a metaphor - the corner of the head caught fire [and also the skull burned].
What is "Kadkod"?
Rashi: Penetrate 1 . Menachem says that it is Makor (like an infinitive).
Rashi citing Targum Yonasan: The honored ones.
Radak: The leaders. This is why they are nicknamed 'the head.'
Malbim: The skull. Refer to 48:45:
The Magihah in Otzar La'azei Rashi says that Rashi explains as if it says Karkar. Indeed, Rashi here is like he explains Karkar (Bamidbar 24:17), and unlike he explains Kadkod (Devarim 33:20, i.e. head). However, Targum Yonasan here is not like the Targum of either of those. (PF)
Who are "Bnei Sha'on"?
Rashi: They are those who raise a voice of beauty.
Mahari Kara: They would go to war with great clamor, amidst their multitude.
Radak: They used to be clamorous and speak great matters. Targum Yonasan is like this.
Malbim: People of big cities, in which there is great tumult and noise.
