So, I found this part interesting while reading (ok, listening to) Book 12.
To whom thus Michael. Dream not of thir fight,
As of a Duel, or the local wounds
Of head or heel: not therefore joynes the Son
Manhood to God-head, with more strength to foil
Thy enemie; nor so is overcome [ 390 ]
Satan, whose fall from Heav’n, a deadlier bruise,
Disabl’d not to give thee thy deaths wound:
Which hee, who comes thy Saviour, shall recure,
Not by destroying Satan, but his works
In thee and in thy Seed:
So the ultimate defeat of Satan will not come by strength of arms, but by strength of heart (blood and ashes, that was a lot cheesier than I intended it to sound.) The Adversary shall not be defeated in the field but removing Satan’s corruption from the world. We saw something similar to this in the description of the war in heaven. When “The Son is set loose on the battlefield, it is not by fighting Satan that he is able to defeat him, but by undoing everything that Satan’s war had done thus far. As we had seen throughout the poem, Satan is a narcissistic, self-aggrandizing, show-off, his guiding star being how others view him. As such, it is a far greater injury than any weapon could do, just to simply erase Satan’s effects, to remove what he has done and deny him his glory.