Rashi: You are angels. I gave to you the Torah on condition that the angel of death will not rule over you any more.

Radak: True judges are called Elohim - "Ad ha'Elohim Yavo Devar Sheneihem" (Shemos 22:8). This is like Tzeva'os (legions) above are called Elohim, for they do their Creator's Shelichus to judge and conduct the world. Hashem is called "Elokei ha'Elohim va'Adonei ha'Adonim" (Devarim 10:17); He is the G-d of the legions above, who are Elohim and Adonim. I said that you will truly be Elohim and resemble upper beings who are also called Elohim, and you will judge straightly, for you have a partnership with upper beings.

Malbim: Just like Elokim's action was needed to create man and the world, so Mishpat and judges are needed for the continued existence of man and the world. Man's nature is social; there will be quarrels, judgments, oppression and robbery which nullifies settlement of the world, if there will not be propriety, Mishpat and judges. In this aspect, they are like Elokim, who forms the world; they are partners with Him in this. 'Any judge who judges correctly, he is considered a partner with Hashem in Ma'ase Bereishis' (Shabbos 10a). They are considered like upper beings, for the primary foundation of Mishpat is based on the encompassing understanding, which is Divine.