1)
Why did he compose a lamentation over him?
1.
Malbim: He was not a commoner. People should cry due to his great level, and the great loss through his death.
2)
What is the meaning of "hak'Mos Naval"?
1.
Rashi: Does he die like a Rasha, through a sword?!
2.
Radak: Does Avner, who was a strong, great man, die like a lowly person, without striking the one who strikes him?!
3.
Malbim: Does he die like a lowly person? He was a great officer for the Jews!