To whom does "Eschem" refer"?
Ramban: Moshe and Yisrael.
Rashbam and Seforno: It refers to Moshe and Aharon.
What was Yisro referring to when he mentioned "from the hand of Egypt" and "from the hand of Pharaoh", and then added "and from under the hand of Egypt"?
Rashi: Because, not only did Hashem save Yisrael from Egypt (a tough nation) and from Pharaoh (a tough king), but He also rescued them from a particularly harsh subjugation to which they were subjected.
Ramban #1: He was referring to two independent miracles; first, to saving Yisrael from the hands of the angry Egyptians (after each plague), and Moshe from the clutches of Pharaoh whenever he came to warn him, 1 and then, to the rescue of Yisrael from the subjugation of Egypt and taking them out to freedom.
Ramban #2 (citing the Ibn Ezra, Seforno and Rashabm): Refer to 18:10:2:1, only he said "Eschem" with reference to Moshe and Aharon, whom Hashem rescued them from the clutches of the Egyptians of Pharaoh.
Inasmuch as Pharaoh was helpless to kill Moshe and Aharon or even to have them removed .