Final answer:
The reader's initial impression of Macbeth when introduced by the nobleman to Duncan is that he is noble and valiant.
Step-by-step explanation:
The reader's initial impression of Macbeth when he is first introduced by the nobleman to Duncan is that he is noble and valiant. This is evident in Duncan's words when he says, 'What he hath lost noble Macbeth hath won.' The reader sees Macbeth as a heroic figure who has achieved victory in battle.