Lady Macbeth..

"Give me the daggers. The sleepign and the dead Are but as pictures... If he do bleed, I'll gild the faces of the grooms withal..." (2.2.69-70, 71-72)

To introduce some background information, Macbeth is told by the three witches that he would become Thane of Cawdor and eventually the King of Scotland. Macbeth is royal to the king and he doesn't believe the prophesy right away. However, it is shown in Act 1 and 2 that Macbeth's royalty is shaken due to the witches' prophesy. Macbeth informs Lady Macbeth of such events before he returns. As he returns, Lady Macbeth incites Macbeth to kill Duncan and become the new king of Scotland. Macbeth finally decides to kill Duncan and succeeds. After Duncan's murder, Macbeth is agitated and brings the evidence (daggers) with him. Macbeth fails to have the courage to hold the daggers and Lady Macbeth takes them.

Lady Macbeth is a woman and women normally don't have the courage to get involved in murder scenes or bloody scenes. However, from the quote we can see that Lady Macbeth is confident and motivated to make Macbeth kill Duncan. She is the actual mastermind of the whole plot in which Macbeth is stirred to follow upon. She is brave and doesn't feel much guilt about the whole murder if she or Macbeth achieves the crown of Scotland.

"Yet who would have thought the old man to have had so much blood in him?" (5.1.41-42)

Macbeth is going through mental breakdowns due to the third prophesy and appearance of Banquo's ghost. It isn't only Macbeth that is having mental breakdowns. Lady Macbeth doesn't show her troubled heart to other people but her heart is visible when she unconsciously sleep walks in her bedroom. Doctor and the lady servant hears the above quote from Lady Macbeth's lips.

The fact that she is lamenting in her unconscious state tells us that she is deeply troubled with Duncan's murder. In Act 2, Lady Macbeth is fearless with the whole plot. She feels unguilty and has the courage to touch the daggers that are covered in blood. Nevertheless, the above quote suggests that Lady Macbeth is actually feeling somekind of guilt and pressure from the murder. Blood in this act symbolizes sin and guilt. Lady Macbeth says, ".... had so much blood in him?" The recognition of having "so much blood" implies huge amount of guilt building inside Lady Macbeth's heart. She is no longer courageous and fearless but fearful and weared out.