Othello belies the whole concept of trust based on reputation as "honest, honest Iago" gets the better of everyone. He foreshadows his deadly scheming that is to come early in the play when he reveals "I am not what I am" (I.i.65). Othello himself, relies on his own misplaced trust of Iago when he requests that he accompany Desdemona to Cyprus: "A man he is of honesty and trust. To his conveyance I assign my wife" (I.iii. 284-285). Othello is always prepared to defend his reputation "My parts, my title, and my perfect soul, Shall manifest me rightly" (I.ii.31-32) he believes and never expects to be let down by a military man.
When Iago begins his assault on Cassio by ensuring that he is implicated in a brawl, Othello is disappointed in Cassio who feels that his reputation is ruined. Cassio has "unlace(d)" his reputation.(II.iii.84). Ironically, it is to Iago that Cassio laments "My reputation, Iago, my reputation!" (253-254).
Iago discusses reputation as it suits the situation, showing how he is a master manipulator. To Othello he says "Good name....Is the immediate jewel of their souls" because he knows what Othello wants to hear but to Cassio he says "Reputation is an idle and most false imposition" (260). Iago relies on confusion and playing to the men's pride to ensure his ultimate goal of destroying Cassio and especially Othello.
The military, the code of honor and the preservation of reputation are all so important to Othello that he will rely for "ocular proof" of Desdemona's supposed infidelity, on a handkerchief he gave her which Iago manages to manipulate into Cassio's possession. Even, as Othello tells Desdemona he is going to kill her and she denies all. "Let him confess a truth" (V.ii.70), Othello mistakes her terror and shock as love for Cassio. He is almost proud of the deed anxious to admit to Emilia that he has killed Desdemona even though he loved her because he feels he can "thy former light restore"(4) through his actions and also prevent Desdemona from "betray(ing) more men."(6)
Even as Emilia expresses her disbelief, Othello is confident that Iago "an honest man he is " (151) and when Iago is exposed for the "viper" that he is and Othello wounds him, it is his honor that spurs Othello to his last act and words. Othello wants it to be understood that he is "an honorable murderer....for nought I did in hate but all in honor" (298). He blames Iago who is apparently a "demi-devil" who "ensnared my soul." (305)He is still concerned that others should remember "I have done the state some service" (341)
The tragedy is assured as Othello dies believing himself "one that lov'd not wisely but too well"(347)