In your analysis, you’re exploring the symbolic significance of clothing in "Macbeth." You're right to connect Banquo's description of the witches as "withered and wild" with their malevolent nature. Their attire reflects their supernatural and chaotic essence, emphasizing their connection to darkness and evil.
Furthermore, when Macbeth exclaims, "The thane of Cawdor lives: why do you dress me in borrowed robes?" (Act 1, Scene 3), the notion of clothing becomes particularly pivotal in illustrating the concepts of identity and ambition. Here, clothing symbolizes power and status, and Macbeth’s use of the term "borrowed robes" reveals his discomfort with the idea of taking on a title that he has not yet earned. It underscores the theme of ambition and the moral implications of usurping power—Macbeth feels that wearing the title of Cawdor is akin to donning a misleading facade that does not reflect his true self.
Connecting this to Lady Macbeth's desire to shed her femininity can further illuminate the theme. She implores the spirits to "unsex" her, revealing her belief that the traits attributed to masculinity—such as ruthlessness and ambition—are necessary to achieve their aspirations and seize power. By rejecting her feminine identity and adopting a metaphorical ‘masculine’ cloak, she seeks to manipulate her own appearance to align with societal expectations of power associated with men.
Thus, clothing in "Macbeth" serves as a powerful motif that reflects the characters’ aspirations, identities, and the moral complexities surrounding ambition. The concept of "borrowed robes" in conjunction with Lady Macbeth’s willingness to abandon her femininity illustrates how both characters grapple with their identities and the societal constructs of gender and power. This intertwining of appearances and inherent traits highlights the dangerous consequences that arise when individuals attempt to wear roles or attributes that do not authentically belong to them.