I know you’re special. So you should have a special character! How you do that is by giving your hero something unique that allows them to stand apart from other heroes. This could be something as innocuous as my neck is unusually long all the way to an exceptional deed like being the only person who has been able to beat the Archmage in a game of chess.
The goal here is not to create a superpower for yourself, but rather to hint at a story hook that the game master (GM) can use to build the world, create a story, or connect you to the world. 13th Age aims for collaborative storytelling so this is your chance to help build the world out more!
Get creative! If you can’t think of anything, maybe ask the GM to either wait and see what develops or if they have any suggestions. Maybe you’ll get talking and figure out the perfect thing.