When Aristotle says the part about “adventitious charm,” that seems to connect to his idea that the noble and the virtuous find so much pleasure in their life as it is that they have “no further need of pleasure.” Pleasant seems to be a kind of self-sufficient, harmonious state.
It appears as if Aristotle thinks of pleasant as the opposite of pleasure. Remember, there’s a part where Aristotle says that most people’s “pleasures are in conflict with one another because these are not by nature pleasant.” Yet to live a happy or pleasant life seems to go along with nature. Perhaps that’s why it’s pleasant and happy—you don’t have to do anything other than act naturally.
As for moral virtues, if you read the first paragraph in book 2, Aristotle clearly states how moral virtues are developed. In case you missed it, Aristotle says moral virtues are fostered by “habit.”
To identify an act as virtuous, it seems like temperance is a key factor for Aristotle. If you eat and drink too much or too little, you are, according to Aristotle, engaging in “excessive and defective exercise.” These are destructive activities that destroy “temperance and courage.”
When you eat and drink enough to maintain a strong, healthy character, then temperance is present, so virtue is as well. Likewise, when you “despise things that are terrible” and stand your “ground against them,” you are showing courage. Remember, both temperance and courage don’t come magically: they come via habit or practice.
In order to find the “mean” of moral virtue, you must find the middle. Aristotle claims the middle is “intermediate.” There is no exact middle. That’s likely why Aristotle says, “It is no easy task to be good.”