My first 2 are a man

My first 2 are a man;

my first 3 a woman;

my first 4 a brave man;

my whole is a brave woman.

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Scroll down for answer and notes.

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I am a fan of letter-riddles like this one! To learn how to make riddles like this, you need to become attuned to words-inside-words (which is kind of like that word game at The Guardian newspaper online, Wordiply).

Heroine.