Yes and no. The feminine and the masculine* contain slight elements of each other, like the white in the Yin/Yang contains a black dot and vice versa. Sarah teaching herself to be a commando is an overexpression of the ingredient of masculinity that makes a tomboy. Overall, she still has a feminine perspective.

Also, Sarah's speech is ironic because it's right after she was on the brink of destroying a man's life.

*edited to remove implication that femininity/masculinity are socially constructed