The scene you want to analyse is Act V scene 8. This is when Macbeth confronts Macduff in his castle and Macduff tells him that he was "untimely ripped" from his mother's womb, meaning that he is not "of woman born" and thus can kill Macbeth. The final speech of Macbeth is particularly interesting to examine, and it can be used to argue that in this final scene, we have to reevaluate the character of Macbeth and to a certain extent he reclaims some of his nobility and honour in the way that he meets his death. Note what he says:
I will not yield
To kiss the ground before young Malcom's feet,
And to be baited with the rabble's curse.
Thought Birnam wood be come to Dunsinane,
And thou oppos'd, being of no woman born,
Yet I will try the last: before my body
I throw my warlike shield: lay on, Macduff;
And damn'd be him that first cries, "Hold, enough!"
These final words and the way in which Macbeth chooses to not accept the cruel fate that destiny and the witches have planned for him meekly bestows a certain amount of dignity upon his ending. Whatever the forces that are ranged against him, and however impossible his situation is, Macbeth is a character who refuses to yield without using all of his strength and might to fight against fate and destiny. Even though he recognises his time is up, his action of continuing to resist makes him a character that we come to respect. Macbeth thus keeps on fighting because it is not in his nature to give in without a struggle. He is a brave and volorous individual, whatever else we may think of him.