What was Sha'ul's defense?
Radak: Their compassion on the animals was not for their benefit, rather, to sacrifice to Hashem, who was with them in the war.
Kli Yakar citing Mahari: The people wanted to spare the animals. I protested, but they did not listen! (He erred. He should have forced the people to fulfill Hashem's command.)
Chanukas ha'Torah (Haftoras Parshas Zachor): Amalek were witches, and could change themselves into the form of animals (like Rashi (3) wrote). However, the eye does not change. If an animal's eyes resemble a human eye, this is a blemish. We saved only animals proper for Korbanos, so there is no concern lest they are Amalekim!
Toras Moshe (Shemos, Haftoras Parshas Zachor. DH v'Nir'eh): Why did Hashem decree to kill even animals? Is it due to concern for witchcraft? This is Chilul Hashem! Is Hashem concerned for witchcraft? Witchcraft does not word against [great] Tzadikim (Chulin 7b), and all the more so against Machaneh Yisrael, in which the Shechinah dwells! Rather, surely the decree was so nothing will remain called on Amalek's name. We will offer them, and nothing will remain!
Malbim: (a) He attributed the action to the people. (b) The purpose was not to take spoils, rather, to sacrifice. The rest we destroyed!
What can we infer from Sha'ul's defense?
Malbim: He thought that it is improper to destroy everything. He did not regret or confess, for he thought that he did not sin at all, rather, he denied and made a false excuse 1 .
Why did he say "Hashem Elokecha"?
Radak: This was to honor Shmuel, to show his level. It is proper to say Elokav or Elokecha about a great person - Nevi'im said "Hashem Elokai" (Yonah 2:7), and it says about a Nasi "Hashem Elokav" (Vayikra 4:22).
