conscience > innermost consciousness

4 Well knowing true all that he did rehearse;

true > [to be true] rehearse > give an account of

5 And to his fresh remembrance did reverse

reverse > recall

6 The ugly view of his deformed crimes,

deformed > perverted, morally repulsive

7 That all his manly powers it did disperse,

That > [So that] manly > {Pertaining to human beings; also: manly, in the modern sense}

8 As he were charmed with enchanted rhymes;