Moses speaks of terror as if it were a person that could forcefully grab hold of someone and make them extremely afraid. AT: "the inhabitants of Philistia will be afraid" (See: [[rc://en/ta/man/translate/figs-personification]])
Moses speaks of people becoming weak from their fear as melting away. AT: "will be weak from fear" or "will be afraid and faint" (See: [[rc://en/ta/man/translate/figs-metaphor]])