en_tn/2sa/17/12.md

come on him

This means to purposefully go to where he is and then to attack. (See: rc://en/ta/man/jit/figs-idiom)

we will cover him as the dew falls on the ground

Absalom's army is described as covering David's army like the dew covers the ground in the morning. Alternate translation: "we will overwhelm and completely defeat David's army" (See: rc://en/ta/man/jit/figs-simile)

dew

the fog or misty cloud of water that can fall onto the ground during the night, covering the ground and leaving it wet in the morning

We will not leave even one of his men ... alive

This negative sentence is used for emphasis and can be stated in a positive form. Alternate translation: "We will kill every one of his men" (See: rc://en/ta/man/jit/figs-litotes)

him himself

Both these words refer to David. Alternate translation: "David himself" (See: rc://en/ta/man/jit/figs-rpronouns)