User blog comment:Hidden Scorpius XI/My impressions on "Two Steps Forward, Two Steps Back" (V4-E9)/@comment-26397825-20170109021619

Yang did say that she and Taiyang have been practising for weeks, so she's had literal weeks of dedicated one on one combat training with another hand to hand fighter to get used to her arm. That's not a Mary Sue trait, that's putting the time and effort in, as well as having a top notch piece of equipment made for you by the top notch technicians of the world.