In an Elizabethan context, the word "honour" means something very different for men and women. For men, there was a conventional "code of honour". This included honesty, reputation, heroism in battle, social status, and male camaraderie. However, this was a vague concept so it can be difficult to distinguish if a man was acting honourably or not, especially from a modern perspective. For a woman, however, her honour simply meant her chastity and devotion to her husband. There is a gender divide in both plays Othello and Much Ado About Nothing, and this may be due to the dual meaning of honour.
Both plays Othello and Much Ado About Nothing start with talk of war. In Othello, a tragedy, they are on the brink of a war, and therefore there is a sense of urgency and anticipation from the beginning. In Much Ado, a comedy, the war is over and the soldiers are returned having honoured their country and not lost many men ("of name", at least, i.e. no one of a high status, or importance). The atmosphere from the start is relaxed and playful.
The men of the two plays share a concern with honour and reputation and, ironically, often act dishonourably as a result of trying to protect their honour. Othello's services in war have earned him a reputation as an honourable soldier. At the beginning of the play, he is aware and assured of this, which aids him when accused by Brabantio. Othello is tricked by Iago into thinking his reputation is in danger: "Good name in man and woman, dear my lord, Is the immediate jewel of their souls" - the word "jewel" emphasises the value of honour, and the word "soul" alludes to the Elizabethan connection of honour with religion and spirituality. When Othello kills Desdemona, he sees this as an act of honour and justice. He kills his wife in an attempt to save their reputation, saying "naught I did in hate, but all in honour.