cecethis

I think it's clear she has a cutie mark purely based on age and accomplishment. We know from twilight's studies cutie magic is unique. Because both earth ponies and pegasi have them it's not unicorn related, thus not horn related. When Tirek steals the pony's magic they all continue to have marks just not their personal magic including: earth strength, pegasi flight, unicorn magic. In reverse, when Starlight stole marks they had basic skills yet no one excelled at anything. At the end of the movie Twilight tells Tempest she and her magic are powerful. So she has clearly found her strength and has magic with the broken horn. She has just been focusing those skills in a less than ideal way. I believe the difference is reaching her full potential in a positive way. Think back to when Diamond Tiara says she knew her special talent was getting other ponies to do what she wanted, she just didn't understand it or what to do with it. Part of the Cutie Mark Crusaders tasks is to help ponies expands on their talents and understand them. Recall bulk biceps who had only been lifting everything in sight but never been a trainer. The real question is what is the mark? What will she do next? She is clearly good at martial arts, determination, commanding/ leading groups. Is Twilight getting a new student?