"Of all the manifestations of power, restraint in the use if that power impresses people most."
Here the argument claims that "Of all the manifestations of power, restraint in the use if that power impresses people most." Which actually depends upon the prespective by which you are looking at it. Power not only always has destructive force only, like the nuclear power as in nuclear bomb; but there's also a form of power that is responsible for the saving of lifes of people like the power of knowledge, by the virtue of which doctors are able to save the lifes. So, it totally depends upon from which prespective you're looking at it.
See, there are various types of powers like power of knowledge, money, arsenal, muscle, and others. But it depends upon us that how do we use it. Like the power of knowledge can be given to those who are in need and can be saved and helped by the virtue of it. Well, let us understand it with an example, let's say that there is a huge guy with a well built physic in your classroom, you see where this story is going; so, he has got two options (on considering his physic), first one is that he should be bossing around (which is not the good option) and the second one is that he should be helping the other students with their worsk without being all bossy and belittling others.
As, mentioned in the above paragraph the first option gives the idea of using all his power to dominate the others, which is not a good way. But tthe second option gives the better idea of conceling his some amount of energy so that other students might not be afraid of him, which will inturn be beneficial to him in some or the other way; and that's the best option that he can choose from. Here, the guy is restraiting his power and this impresses most of his classmates. Now here, at this point of time the statement seems to be proven true, which is not at all, because as I've already mentioned that it depends upon your prespective.
But it isn't all, see if your've got a great defence power and there is a war, in that scenario you can't restraint your power and thought that people within your reach to protect your people. So, the conclusion of the whole story is that it depends upon the type of manifestation of power and the scenarios which require them; results in the surther action that, wheather we should be restraiting it or unleashing it.