What does it mean by "becoming" when Joey said "It(a bag) is as handy as **it is becoming**"?
The episode is from "Friends", where Joey discovers both the stylish allure and functionality of the "Man Bag." (His friend, Rachel recommended him one for his audition, saying the bag is "unisex". Joey didn't like it at first but gradually finds himself getting fond of the item.)
And Joey and all his friends are at the coffee house, his male friends still make fun of the bag.

Joey: "I'm off to my audition, how do I look?" (showing off his bag to everyone.)
Rachel: "It looks great. Joey, it's gonna get you that part."
Chandler: "And a date with a man."
Joey: "You know what? make fun all you want. This is a great bag. It's as handy as **it is becoming.**"

Here, I'm confused about the meaning of the phrase, since the word "becoming" has its own definition as an adjective, "flattering a person's appearance", but I saw online that the meaning is "up and coming", which I guess is to imply that it's gonna be more successful in the future?

What does the sentence exactly mean here?
Thanks in advance.

Question

What does it mean by "becoming" when Joey said "It(a bag) is as handy as **it is becoming**"?
The episode is from "Friends", where Joey discovers both the stylish allure and functionality of the "Man Bag." (His friend, Rachel recommended him one for his audition, saying the bag is "unisex". Joey didn't like it at first but gradually finds himself getting fond of the item.) 
And Joey and all his friends are at the coffee house, his male friends still make fun of the bag.

Joey: "I'm off to my audition, how do I look?" (showing off his bag to everyone.)
Rachel: "It looks great. Joey, it's gonna get you that part."
Chandler: "And a date with a man."
Joey: "You know what? make fun all you want. This is a great bag. It's as handy as **it is becoming.**"

Here, I'm confused about the meaning of the phrase, since the word "becoming" has its own definition as an adjective, "flattering a person's appearance", but I saw online that the meaning is "up and coming", which I guess is to imply that it's gonna be more successful in the future?

What does the sentence exactly mean here?
Thanks in advance.

Answer

It's as handy as **it is becoming.**"

He is saying the bag is both useful (handy) and it really suits him. ie he looks good with it. 
'becoming' is not really a word often used to describe a male 'looking good' - it's reserved more for females. So when he says this, the speaker is self-mocking or poking a little fun at himself.

Answer

"Becoming" simply means good appearance. If something is "becoming" it means it makes you look good. I've never seen another definition.
For example, a friend of mine who respected me very much had an argument with me. I was getting angry, and he said this "stop getting angry, it's not becoming."
In other words "Stop getting angry. You usually look good, and I usually respect you, but not now."