Question

How did Macbeth feel seeing the dagger?

Answer 1

Yet, he starts to wonders if the dagger which he sees is a 'fatal vision' or a mere hallucination. Macbeth wonders if this dagger is a result of his 'heat-oppressed' or fevered brain referring to his growing insanity. Being it a part of the great tragedy, the soliloquy comes with implied stage direction.

Answer 2

Continuing to gaze upon the dagger, he thinks he sees blood on the blade, then abruptly decides that the vision is just a manifestation of his unease over killing Duncan. The night around him seems thick with horror and witchcraft, but Macbeth stiffens and resolves to do his bloody work.