I've always thought that we don't use articles when the adjective is descriptive as in "Welcome to fabulous Las Vegas". And that we do use them when the adjective makes the proper noun different from its original form as in "The bewildered Smith has arrived" (that is, as opposed to Smith's regular condition). But I don't think that's true, since I'm only guessing. So, what's the rule for that one?
Articles in this sense are difficult to put. There are many idioms with and without articles that spin my head. I have referred many dictionaries and grammar books to learn articles but what I found were guidelines, and never rules!
I feel that the articles are used with proper nouns when the identity, form, state or character of those nouns change. It has least to do with adjectives.
The Kabul back then was calmer and peaceful.
It takes the definite article the because back then, the identity of Kabul was different than what we have today.
However, in the second sentence, it is acceptable. Because, the state of Smith is changed:
The bewildered Smith has arrived.
Also, take a note that if a personality is very famous, they take articles.
The great Hippocrates contributed a lot to the medical science.
You also use an article to refer to someone's character, and not literally that person.
You don't expect everyone to be a Mother Teresa.
Again, if you don't know a person and still want to define him/her as someone, use indefinite article.
There is a John Anderson on phone.
There is much more in articles but this is what all I felt covering here.