Thou, even thou, art to be feared - To be had in reverence or veneration. The repetition of the word “thou” is emphatic, as if the mind paused at the mention of God, and remained in a state of reverence, repeating the thought. The particular “reason” suggested here why God should be had in reverence, was the display of his power in overthrowing by a word the mighty hosts that had come against the holy city.
And who may stand in thy sight - Who can stand before thee? implying that no one had the power to do it. “When once thou art angry.” If such armies have been overcome suddenly by thy might, then what power is there which could successfully resist thee?