How does Othello lose his honour and noble stature through his insecurity in Shakespeare's Othello?I know Othello loses his honour because he kills...

I would pay attention to the gradual disintegration of
Othello's state of being in the world.  Over time, Iago's insinuations and calculations
end up destabilizing Othello.  The proud and towering figure that is seen at the start
of the play is little more than a gutted shell at the end of it.  Even at the end of the
play, Othello is concerned about his reputation and how others will see him in the light
of his actions.  This reflects how perception and reality were always blurred in
Othello's mind, reflecting that his honorably and noble stature were always suspect and
built on a shaky firmament:

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Othello is concerned how this will be
reported abroad. He is concerned about his reputation, but he is more concerned with the
truth. He humbly points out that he has done 'some service' to the state of Venice, a
mild understatement. As far as his crime, he wishes it to be told fully, without toning
down his flaws or making him more of a monster than he feels he is. His simple statement
is that he 'loved not wisely, but too
well.”

This idea
of a weak firmament of character becomes the fundamental root of Othello's insecurity,
precluding him from being able to act in the name of what is right.  Instead, this
compels him to act in the name of what he perceives to be right, and this perception-
driven action is what undermines all the good and nobility within his
character.