Cyrano de Bergerac, being a man of intense chivalric honor, believes his actions to be more important than his physical self; he thinks that since mockery and derision are inevitable -- because of his large nose -- he must prove his worth through deeds. It doesn't occur to him until near his death that he can be worthy of love and respect without those deeds; instead, he is convinced that he must prove himself over and over. This eliminates his "sense of self," since he cannot perceive his own worth, only the worth of his acts. This can be clearly seen in his promotion of Christian, whom he believes worthy (because of physical appearance) of Roxane's love:

CYRANO:
(aside--drawing his sword):
Ay, and let me die to-day,
Since, all unconscious, she mourns me--in him!

Cyrano is willing to keep these secrets as a chivalric act; he will not suffer Christian to be humiliated because Christian cannot create poetry and wit, but instead allows his own wit to be attributed to Christian so that Roxane can be happy. Later, as he prepares to die, Cyrano makes a last symbolic stand against the Sins of Man, which he has fought all his life:

CYRANO:
...I know you now, old enemies of mine!
Falsehood!
(He strikes in air with his sword):
Have at you! Ha! and Compromise!
Prejudice, Treachery!. . .
(He strikes):
Surrender, I?
Parley? No, never! You too, Folly,--you?
I know that you will lay me low at last;
Let be! Yet I fall fighting, fighting still!
(Rostand, Cyrano de Bergerac, gutenberg.org)

It was a backstabbing attack that mortally wounded Cyrano, the worst kind of Human Sin that he could imagine, and yet he refuses to simply give in. Instead, he discovers the single thing about himself that he can pass on, the true "self" that is distinct from his actions and superficial appearance; his "panache," the personal sense of achievement that he can hold up. Cyrano has never compromised his ideals, and never held himself as something he is not; he has protected the honor of others, and allowed his own suffering so others may rejoice. In his dying moments, Cyrano truly understands his own self-worth, the worth that would -- and does -- make him attractive to Roxane despite his nose; he is a man of courage and convictions, and that elevates him above even his great deeds.