Unfortunately for M., the adjectival form of his name (Machiavellian) has come to mean something rather different from his actual ideas. His political philosophy would be best described as realpolitik.

Today, we often view the word realpolitik in a somewhat negative sense, because the underlying assumption is that a ruler should be 'good' first and effective second. This is a modern assumption.

What this article doesn't delve into is the idea of virtù itself, and specifically how (someone like Nietzsche) sees this value and the Renaissance in general as a return to pre-Christian, pre-Platonic ideals of excellence, ones that precede modern ideas of good and evil. It is an idea intimately tied up with aesthetic concerns of self-mastery, clarity, and the dispelling of Platonic (subsequently Christian) idealism. Machiavelli himself was quite interested in the ancients, so this is not surprising.

https://plato.stanford.edu/entries/machiavelli/#PoweVirtFort

https://en.wikipedia.org/wiki/Virtù

This excerpt from Twilight of the Idols (Nietzsche) is maybe the best brief description of the idea. Sorry for the length, the part about Machiavelli specifically is in the third paragraph.

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I am not indebted to the Greeks for anything like such strong impressions; and, to speak frankly, they cannot be to us what the Romans are. One cannot learn from the Greeks—their style is too strange, it is also too fluid, to be imperative or to have the effect of a classic. Who would ever have learnt writing from a Greek! Who would ever have learned it without the Romans!... Do not let anyone suggest Plato to me. In regard to Plato I am a thorough sceptic, and have never been able to agree to the admiration of Plato the artist, which is traditional among scholars. And after all, in this matter, the most refined judges of taste in antiquity are on my side. In my opinion Plato bundles all the forms of style pell-mell together, in this respect he is one[Pg 114] of the first decadents of style: he has something similar on his conscience to that which the Cynics had who invented the satura Menippea. For the Platonic dialogue—this revoltingly self-complacent and childish kind of dialectics—to exercise any charm over you, you must never have read any good French authors,—Fontenelle for instance. Plato is boring.

In reality my distrust of Plato is fundamental. I find him so very much astray from all the deepest instincts of the Hellenes, so steeped in moral prejudices, so pre-existently Christian—the concept "good" is already the highest value with him,—that rather than use any other expression I would prefer to designate the whole phenomenon Plato with the hard word "superior bunkum," or, if you would like it better, "idealism." Humanity has had to pay dearly for this Athenian having gone to school among the Egyptians (—or among the Jews in Egypt?...) In the great fatality of Christianity, Plato is that double-faced fascination called the "ideal," which made it possible for the more noble natures of antiquity to misunderstand themselves and to tread the bridge which led to the "cross."

And what an amount of Plato is still to be found in the concept "church," and in the construction, the system and the practice of the church!—My recreation, my predilection, my cure, after all Platonism, has always been Thucydides. Thucydides and perhaps Machiavelli's principe are most closely related to me owing to the absolute determination which they show of refusing to deceive themselves and of seeing reason in reality,—not in "rationality," and still less in "morality." There is no more radical cure than Thucydides for the lamentably rose-coloured idealisation of the Greeks which the "classically-cultured" stripling bears with him into life, as a reward for his public school training. His writings must be carefully studied line by line, and his unuttered thoughts must be read as distinctly as what he actually says. There are few thinkers so rich in unuttered thoughts. In him the culture "of the Sophists"—that is to say, the culture of realism, receives its most perfect expression: this inestimable movement in the midst of the moral and idealistic knavery of the Socratic Schools which was then breaking out in all directions.

Greek philosophy is the decadence of the Greek instinct: Thucydides is the great summing up, the final manifestation of that strong, severe positivism which lay in the instincts of the ancient Hellene. After all, it is courage in the face of reality that distinguishes such natures as Thucydides from Plato: Plato is a coward in the face of reality—consequently he takes refuge in the ideal: Thucydides is master of himself,—consequently he is able to master life.

http://www.gutenberg.org/files/52263/52263-h/52263-h.htm#THI...