Why did he change the names only of these four?
Malbim: Only these entered the king's service. It is the king's way to change names, like Nebuchadnetzar changed Tzidkiyah's name.
What is the significance of "Belteshatzar"?
Rashi: The idolatry of Bavel was called Bel ? "Di Shmei Belteshatzar k'Shum Elohai" (4:5). Belteshatzar is an expression of Chochmah in Arame'ic.
Ibn Ezra: This is like Pharaoh called Yosef Tzafnas Pane'ach. Rav Sadya Gaon says that Bel and Tzar are Arame'ic. We find other Bavli names that end in Tzar ? Nebuchadnetzar, Belshatzar, Sheshbatzar.
Malbim: This was Nebuchadnetzar's god. He immediately saw a Divine attribute in Daniel. The names given to Chananyah, Misha'el and Azaryah were not of idolatry.
