Lady Macbeth received Macbeth's letter about witches' prophesy and became ambitious, immoral and a tempter. She did say
Unsex me here
But this has nothing to do with her gender, a lot of times it has happened in history that women have played deceitfully, immorally and cruelly for example you can take Helena, wife of Chandragupta Maurya and daughter of Alexander's General Seleucus Nicator, was cruel and ambitious too.
The only way for Lady Macbeth to gain power is through Macbeth using her rhetoric.
That was true, she rewired the brain of Macbeth (which was already fighting with the ambitious Devil) and made him to do what he feared. But not only she used rhetoric but also showed masculinity by taking the blooded daggers from Macbeth and placing it there. But again this rhetoric persuasion should not be related with gender, as we find in Julius Caesar; Cassius persuaded Brutus with murderous thoughts.
Do you think that the tragedy of Macbeth is the consequence of Macbeth is being too sensitive to masculinity? What does Masculinity mean for Macbeth?
Macbeth was not less masculine, in Act 1 Scene 2 he is depicted as:
for brave Macbeth – well he deserves that name
and he is considered violent too:
He unseamed him from the nave to th’chops
but it is unjust to think of his pure conscience as a sensitive masculine character, he after murdering the king Duncan expresses his inner voice as:
I am afraid to think what I have done;
Look on't again I dare not.
So, considering the above saying of Macbeth and comparing it with "He unseamed him from the nave to th’chops" it doesn't seem that Macbeth was afraid of blood, he was afraid of himself and Higher Self, even at his death his last words were
. . .my soul is clog’d with blood—
I cannot rise! I dare not ask for mercy—
It is too late, he drags me down; I sink,
I sink, — my soul is lost forever! — Oh! — Oh!
He thinks and worries about his soul, his feeling of guilt was overtaking him. The hallucination of Banquo was just another portrayal of how deeply Macbeth was aware of his murderous sin.
There are some of the lines in Macbeth that do demonstrate gender hierarchy, Macbeth said to Lady Macbeth
Bring forth men-children only;
For thy undaunted mettle should compose nothing but males
and Witches warned Macbeth
Macbeth! be bloody, bold and resolute;
laugh to scorn the power of man;
for none of woman born shall harm Macbeth.
To re-quote your question
What does Masculinity mean for Macbeth?
Macbeth was valor, and respected by whole men of Duncan. Macbeth knew what sins always bring to the sinners at last, his extreme feeling of guilt and consequential hallucination was because of the transparency of his heart.