998 B
The one who will dash you to pieces
The word "you" refers to Nineveh. Nahum speaks of an army or military leader destroying Nineveh as if he were to shatter Nineveh like one would shatter a clay pot. See how you translated this in Nahum 2:1. Alternate translation: "The one who will destroy you" (See: rc://en/ta/man/jit/figs-metaphor)
in their march
The word "march" can be translated as a verb. Alternate translation: "as they march" (See: rc://en/ta/man/jit/figs-abstractnouns)
The large shield is made ready to protect these attackers
This can be stated in active form. Alternate translation: "The attackers make ready the large shield to protect themselves" (See: rc://en/ta/man/jit/figs-activepassive)
The large shield
This refers to a large cover that those who besieged a city would set up over themselves and their battering rams to protect themselves against the arrows and other projectiles with which the people in the city would attack them.