Just As I Once Was

The students gathered in the courtyard the next day, eager to hear Princess Twilight's selection. When they were all assembled, she cleared her throat and began. "So this is the big day, huh? One of you is going to become my apprentice." She looked out over the assembled ponies. "Before I tell you the two candidates, I would like to explain the rules of the selection. If you are picked, you will fight the other candidate in a magic duel until one of you surrenders or I pull the plug. Understand that the conditions of this magic duel are different than a traditional magic duel. This is an actual fight."
The assembled students showed varying signs of understanding.
"All right, are you ready to hear my selections?"
"Yes," the class answered as a unit.
"My selections are...Dinky Hooves and Sweetie Belle."
Dinky and Sweetie came forward, the former glaring at the latter in a predatory manner. Dinky's long, blonde mane was tangled and knotted. It seemed as if she'd just rolled out of bed. Her tail swished back and forth, framing her cutie mark: a white circle with a black question mark in the center.
Sweetie Belle cowered a little under Dinky's hard gaze, but held her ground. Her mane was dead straight and cut a little roughly, and a mark of a stylized heart with a music note on the inside (resembling a keyhole, somehow) graced her flank.
"Do you two understand the rules?"
"Yes."
"Yeah."
"Are you prepared?"
"Undoubtedly."
"As much as I'll ever be."
"Then begin."
Dinky started almost instantly, hurling dark red magic bolts at Sweetie Belle.
Keeping a cool head, Sweetie dodged most of the dark bolts, even going so far as to absorb a few with a magic shield.
Dinky growled. "I won't let you win, you stuck-up nag. This apprenticeship is MINE!!" Dinky charged and crossed horns with Sweetie Belle.
Sweetie gritted her teeth and shrouded her horn with magic. "I won't go quietly. I have no doubt that you're better than me...but I want this just as much as you, so I'll put up a fight!!" Sweetie pushed her back. She charged, intending to catch her off-guard.
Instead, Dinky hardened her magic into a blade around her horn and made a slashing motion.
Half of Sweetie Belle's horn fell to the ground.
Sweetie Belle cried out in surprise and staggered back, eventually sagging to the ground.
Dinky stood over her foe, grinning triumphantly. "Oh, would you look at that. Poor, spoiled Sweetie can't use her magic anymore. Why don't you surrender and save yourself the embarrassment?"
Sweetie Belle's eyes flashed a brighter green, and Dinky suddenly flew backwards. Sweetie Belle struggled to her feet.
"You can't cut me off from magic just because you cut off my horn. Remember what Miss Twilight said: 'Magic is mental.'" Sweetie walked over to Dinky, who was still struggling to her feet.
Dinky lashed out at Sweetie, who easily blocked the attack.
"Damn...you...I...will...never...surrender!"
Twilight watched this continue for a few minutes, then let her voice ring out. "That is enough!!"
Both combatants stopped immediately.
Twilight walked down from her pedestal. "That's all I need to see." She turned to Dinky first. "Dinky, you had the potential I was looking for, but you let your anger control you far too easily. I would attempt to wean you from relying on your anger, but it seems to be a very deep-seated behavior. I am sorry, but you will not become my apprentice." She turned to Sweetie Belle. "Congratulations, Sweetie Belle. Though your skills may be limited, your eagerness to work hard and try learning new concepts is invaluable for an apprentice. You, Sweetie Belle, are from this day forth my apprentice."