What is "Morah"?
Rashi #1: It is authority and a yoke.
Rashi #2: It is an expression of casting - "Yarah va'Yam" (Shemos 15:4).
Rashi #3: It is an expression of a razor 1 .
Radak, Malbim: Fear 2 . Radak - cause them to fear You. Malbim - make them fear You Yourself, and not a human who agitates the land.
Surely "u'Morah Lo Ya'avor Al Rosho" regarding Shimshon (Shoftim 13:5) is a razor, for the verse says that he was a Nazir. Tana'im argue (Nazir 66a) whether the same applies to Shmuel (I, 1:11), or if there it refers to fear of people. (PF)
Is it not already known that they are human?!
Rashi: It let blood known that they are not Divinity, to rule via their strength.
Radak: It will be known that they have no strength against Elokim.
Malbim: Nations will know not to fear them, for they are lowly humans. Why make them the staff of Your anger (refer to 9:20:2:1), and people will fear them?!