Can one strengthen Hashem?!
Radak: With your words, attribute the Oz to Hashem. His strength gave you vengeance against your enemies, and not your strength.
Toras ha'Magid (118:23): Hashem constricted Himself to be like a receiver, in order to make us rejoice, that He gets pleasure from us - "me'Es Hashem Haysah Zos Hi Niflas b'Eineinu."
Malbim: Miraculous conduct for Yisrael is only when they are worthy of it based on their deeds 1 . Prepare yourselves via good deeds; through this, you give strength to Kel to conduct in this higher way.
Malbim (Yeshayah 48:2): When Yisrael do not deserve, Hashem one does wonders in front of them, so they will believe in Him. (Perhaps then the general conduct is natural, just isolated wonders are done to instill Emunah, e.g. Eliyahu on Har ha'Karmel. This is unlike in the Midbar, in which there were constant miracles - manna, the well, the clouds, the pillar of fire
What is the meaning of "Al Yisrael Ga'avaso v'Uzo ba'Shechakim"?
Radak: The prefix Vov in v'Uzo equates what came before it to what follows it, like the Vov in "Mayim Karim Al Nefesh Ayefah u'Shemu'ah Tovah me'Eretz Merchak" (Mishlei 25:25). I.e. just like His strength is seen ba'Shechakim - "ha'Shamayim Mesaperim Kevod Kel" (above, 19:2) so His Ga'avah (grandeur) is seen on Yisrael; He fights enemies for them with Ga'avah and strength.
Malbim: In Kisvei ha'Kodesh, Ga'avas Hashem is acting miraculously. In this He had pride and is elevated over nature. This conduct is fixed ba'Shechakim, above Shamayim and the Ma'arachah. His Ga'avah and Oz to conduct miraculously is on Yisrael, i.e. only for them, and only if they merit via their deeds.
