1)
Why does it say "Ha'irah Fanecha Al Avdecha"?
1.
Radak: Al is like El; we find "Ya'er Hashem Panav Elecha" (Bamidbar 6:25). The radiance of His face is salvation and success.
2.
Malbim: Save me via open Hashgachah, so all will see Your face and Hashgachah.
2)
Why did he say "b'Chasdecha"?
1.
Radak: [Save me] even though I am not worthy.
2.
Malbim: There is no limit to Chesed.
