> Kinda made his story sad, but not exactly tragic
He had a horn, but wasn't exactly able to use everyday magic without a magic enhancer (I made it up, it's a ring that goes around a developing unicorn's horn that enhances magic for training). Of course, Berry was more confused when his cutie mark is an explosion. He was the first of his class to get his. As a colt, he was proud and showed it off but as he grew older, being that it appeared seemingly without reason it felt ominous. As a full-grown unicorn, he still went around with an enhancer, but his magic started to fade, growing weaker and weaker until he couldn't use it anymore and had to go to a doctor to check it out. The doctor had no idea and sent him home, hesitantly saying Berry is just fine. While he's helping out a certain mad scientist friend, an experiment triggered his horn (more like the large amount of magic that was just storing up in him) and a large explosion occurred and much of his horn crumbled due to it not handling it.
Berry was hospitalized for a bit, but not much else is wrong with him. He for sure has no magic in him anymore. Berry was at first shocked and saddened about it, but soon, he felt a large weight off his shoulders. Finally, that ominous feeling is gone and he knows what's going on and he can just live his life now. It's still getting used to, but he's adjusting very well.