People seemed to immediately find her off-putting when she first debuted, similar to Weiss. A magnified version in a manner of speaking. Her harsh and strict nature is a form of motivation, akin to a drill sergeant and evidently a result of being in the military. > https://twitter.com/alle1304/status/1287413231821168640

Weiss has always struggled with feeling inadequate and dissatisfied due to the concept of perfection being ingrained since childhood. She's had difficulty being proud of herself. How her older sister acts is purely to remedy her lack of faith and confidence. Winter obviously >

loves and adores Weiss, the pride and joy of her life. She wants the best for her and for her to succeed. So when Weiss starts displaying a lack of hope, Winter has to restore it through a more effective means since she knows she can't always be there to protect Weiss. >

The only way she truly could was by teaching her how to protect herself.

As of Volume 7, we see just how strong their sisterly bond is. She's always been loyal to a fault, just following orders without further questioning until Penny acted as her polar opposite conscience and >

swayed her to put her feelings first for once. Hence her withholding the entire truth and giving them a head start, since she knows they're in the right. Winter helped them through subtle acts so as to not completely defy Ironwood, but undoubtedly will in the end.