A single positive qualifier to the tiny form of address sir results in dramatic irony in this scene because the reader/spectator's knowledge of Macbeth's crime clashes with the meaning of honour and perfect qualities expressed by the adjective noble.
It is very relevant to point out the similar connotations expressed by the positive qualifier added to the form of address lady.
Shakespeare makes this form of address ironic with a slight shift of emphasis on the closeness of social relations, e.
Shakespeare also exploited the meaning of the noble form of address lady with qualifiers.
What becomes Silvia seeing Proteus at her window out of the form of address gentle lady is hideously distorted in the meaning gentle lady addressed to Lady Macbeth who had just urged her husband to kill King Duncan and herself assisted the crime.
As is evident from the examples, Lord is a more emphatic form of address than sir, although it had similar applications.
Like with the other forms of address, Shakespeare exploits the possibility of using qualifying words with the form of address my lord to increase its expressiveness.
The form of address my good lord is fairly frequent in Shakespeare's plays and expresses tenderness and even attachment.
In his use of this form of address in his plays, Shakespeare essentially complies with the above described norm of usage.
It is only in Macbeth that the regular politeness expressed by the form of address madam sounds extremely undeserved.
Rarely used qualifying words with the form of address madam, as, for example, from the Cardinals to Queen Katherine in King Henry VIII, increase the emotive colouring of this form of address.
But one form of address has been left out and deserves mentioning.