1)
Why does it say that Hashem supervises from Shamayim?
1.
Radak (14:2): Even though He is high above them and hidden from them, he oversees them.
2)
What is "Maskil Doresh Es Elokim"?
1.
Radak (14:2): He is prudent to seek Hashem, and thinks that there is Elokim who judges.
2.
Malbim: Even though there were some officers among them who showed honor to Hashem, like Chazal said that Nebuchadnetzar 1 and a few others [in Sancheriv's camp] survived, Hashem saw that they do not seek Him through intellect, to know His Emes and ways.
1
Sanhedrin 96a: Bal'adan sent a letter 'Shalom to Melech Chizkiyah