John Gill Commentary Daniel 5:19

"and because of the greatness that he gave him, all the peoples, nations, and languages trembled and feared before him: whom he would he slew, and whom he would he kept alive; and whom he would he raised up, and whom he would he put down." — Daniel 5:19 (ASV)

And for the majesty that he gave him
The greatness of his power, the largeness of his dominions, and the vast armies he had at his command:

all people, nations, and languages, trembled and feared before him ;
not only those that were subject to him, but those that had only heard of him: who dreaded his approach unto them, and their falling into his victorious hands, and being made vassals to him:

whom he would he slew; and whom he would he kept alive ;
he ruled in an arbitrary and despotic manner, and kept the power of life and death in his own hands; whom he would he put to death, though ever so innocent; and whom he would he preserved from death, though ever so deserving of it; he had no regard to justice, but acted according to his own will and pleasure. Jacchiades renders the last clause, "whom he would he smote": but both the punctuation of the word, and the antithesis in the text, require the sense our version gives, and which is confirmed by Aben Ezra and Saadiah:

and whom he would he set up: and whom he would he put down ;
according to his pleasure, he raised persons from a low estate to great dignity, and put them into high posts of honour and profit, as he did Daniel: and others he as much debased, turned them out of their places, and reduced them to the lowest degree of disgrace and poverty; and all according to his absolute and irresistible will, without giving any reason for what he did.