What does the verse teach about the radiance?
Rashi, based on Targum Yonasan: On that day, His radiance will be like the light of the seven days of creation.
Radak: This is what the Torah said "u'Mar'e Kevod Hashem k'Esh Ocheles b'Rosh ha'Har" (Shemos 24:17).
Malbim: Nogah is something that does not have its own light, just it reflects light that it receives, e.g. the moon receives from the sun. Also in the Nimshal, even though Hashem's light is not revealed in the land, for Shamayim covers His glory, there is only Nogah of the light. Even so, it will be like the light itself. I.e. people perceive Nogah of Hashem's praise and light as if they grasped His light itself. Even though the Hashgachah will be hidden, it will be enough to recognize His light.
Why does it mention "Karnayim"?
Rashi: It is an expression of light that punctures and shines through a hole, like horns jut out. The same applies to "Ki Karan Ohr Panav" (Shemos 34:29).
Radak #1: This refers to the horns of light that radiated from Moshe's face. It says Karnayim (plural) because there are two sides of the face (light radiated from each side).
Radak #2: This refers to the Luchos that He gave to Moshe. They were two, and they shone in what is visible and in what is hidden.
Malbim: From the light will be an Atzeilus ('copied' emanation) of horns of Nogah. Also the Nogah will radiate a great light that all will recognize. I.e. also hidden Hashgachah will send horns of light and flashes, and all will know His Hashgachah.
Why does it say "mi'Yado"?
Rashi: This came to them from His hand.
Radak: The light that radiated from Moshe's face was from Hashem.
What is the meaning of "v'Sham Chevyon Uzo"?
Rashi citing Targum Yonasan: There His strength was revealed, which previously was concealed above. Radak #1 ? there was not such a day before or after, when Hashem was revealed in His great honor, as on Har Sinai, to the eyes of all of Yisrael.
Radak #2: This is the hidden strength of the Aron, like it says "Atah va'Aron Uzecha" (Tehilim 132:8); the Luchos were concealed there.
Malbim: Even though Hashem is hidden and does not appear, He is found in the Nogah. He is alive and lasting ? "b'Kerev Shanim Chayehu" (2).
