"Surely" is expressing an expectation that what follows will certainly come to pass.
# your angry judgment against humanity will bring you praise
Possible meanings are 1) "people will praise you because you are angry at the wicked and judge them" or 2) "people who are angry with you will do things that cause people to praise you."
# you gird yourself with what is left of your anger
Yahweh's anger is spoken of as something that he can tie around himself like a belt. AT: "you tie your remaining anger around you like a belt" (See: [[rc://en/ta/man/translate/figs-metaphor]])