How is Han Fei Tzu a non-Greek rhetoric? (Rhetoric proves opposites, right? so you know to ask yourself how is it also Greek? Without both, you can't do either well, even if in the end you present an answer to only one. Think like a rhetor. )
To answer a question like this you need first to define Greek rhetoric and to do this you have to be careful, since there's no such thing as Greek rhetoric except in so far as you can define it convincingly. I'd start with the concepts of isagoria and isonomia, the foundations of the admittedly debatable assertion or even the myth of equality among Greek men with citizen status. the premise is that anyone has as much right to assert his opinion as anyone else and to argue fearlessly for what he thinks is right. if he prevails, and his goal is to prevail, he is triumphant and can within the bounds of good taste, take public pride in his success.
Now obviously an advisor to an emperor who has life and death power over anyone with little concern for repercussions isn't in a position to argue openly, and if he, the advisor, should prevail, he cannot take credit or assume any benefit can come of it. Indeed, success might bring disaster. Thus whereas Greek rhetoric is open and toe to toe, Han Fei Tzu'e rhetoric is covert and obsequious. It must be hidden and carefully so.
So the power dynamic is significantly different as a result of the different constitutional settings. on the other hand, both rhetorics are a function of the constitutional settings, and this they have in common. The desire on the part of the rhetor to prevail is also shared, but as I said prevailing comes with very different results in both settings.
Theophrastus's characters seem more like stereotypes from drama, comedy specifically, and thus suggest a move in the direction of literary composition which Kennedy argues is the drift of classical rhetoric post Aristotle. We see here descriptions that are interesting in them selves but not very realistic. At best they are exaggerations. Perhaps they have some truth to them, in the sense that such people exist but in a less vivid form. The joy is in the generalizations. a lawyer could use them as models, perhaps, to construct a useful impression of an actual person, but they obviously conflict with our ideas about realism. but this brings up the idea that "realism" is a moderns idea. For rhetoric, things as they are said to be is more important than things as they are or might truly be. prevailing public opinion is what matters. one might feel differently from what a convention dictates, but one would not try to use such a personal conviction in a public debate. it just wouldn't likely work. unless of course one had developed a following by force of character or reputation for success. a general who had one an important battle might have some attitude. but appropriateness is a control on personal expression. rhetoric is a form of social control in this way, a dispersed form of power, as Foucault would have, probably did, say.
The idea of knowing your audience is first expressed by Plato in Phaedrus. Aristotle fleshes it out a bit with his section on characters and on virtues, since one can use enthymemes about virtues and vices to construct impressions of people. Theophrastus takes the same idea up, but goes in a less logos-centric direction by offering dramatizations of character types. since there are individuals rather than audiences, per se, one can doubt their utility as rhetorical advice, by aristotle's notion at least that rhetoric persuades groups no individuals. At any rate, the rhetorical use would have to be, if there is one, in being able to paint one's opponent or invert the characters to characterize positively a person one would praise. Once might extend a given character to a people or a national ethos, though that's no doubt very risky. As a pedagogical practice, having students create characters might be useful or at least interesting. I have had students type the students one can see outside in the courtyard. First they are to divide them into categories or general types based on appearance, clothes, activities, and then describe their "character" and the kinds of things one would hear such a person say.
Possible exam questions for Lu Chi. Lu Chi's prose poem quite closely parallels the Greek idea of the 5 canons. Which of the five terms goes most closely with which section and what do you find interesting about the parallel? How do you describe your writing process? what do you like and what do you wish you did better? and how do you want to improve it?