Whom is a Mary Sue

But she is not 20, she is 100.  100 years of experience and education, if anything they underplay what she and any other stupidly long lived species should be capable of. The krogan for example shouldn't just be fantastic fighters because they are armored regenerating murder turtles but because they have fought for 100s of years.  And many of the things you bring up are exactly why she isn't one, its like people don;t know what the term means.  Its not being talented that makes you one, its displaying the ability with no logical reason why you'd have those skills. Being 100 with 2 bad ass influential moms helps quite a bit explaining why she has multiple skill sets developed to a high degree.