I tried to clarify the last concept. Thank you for helping me.
1) The image is of the face which loses its healthy red colour and becomes pale when the body is sick. The kind of thought which prevents men from committing suicide is not far from a moral conscience.
2)The effect of the whole passage is to make the audience consider what the meaning of “cowardice” is. If it is brave to kill oneself, and cowardly to remain alive, then conscience makes cowards of us all.
3) Hamlet regards courage as the ability to cross the border between life and death, and cowardice the ability to stay alive and bear the pain of human condition.
Put the word cowardice in italics in #s 2 and 3.
Put a comma after cowardice in #3.