There’s no such thing as a character flaw. There are character traits, yes, and they are perceived as desirable or not desirable based on how you would like to be.

It’s not hard to see, because the same trait can be described as a flaw or a strength, compare:

Shy vs. reserved

Confident vs. arrogant

Cowardly vs. careful

So, if you perceive any particular character trait as a flaw, you will be drawn to other characters which have the opposite trait, hoping to learn from them, and repelled by characters who have the same trait because they remind you of yourself. But if you perceive a character trait as a strength, you will be drawn to similar characters and secretly despise those who have the opposite trait.

This is why the same person can be perceived very differently depending on who you ask. Some might describe him as confident, some as arrogant.

The best way to get out of this mess isn’t trying to work on your flaws, but seeing that there’s no such thing as flaws, and all character traits are supremely superficial. You can only do that by learning to no longer care about what other people think of you, and that takes the ultimate courage - way more courage than becoming brave, which is simply another character trait that can also be described as reckless depending on who you ask. ;)