She's part of Brad's events. If you talk with a certain guy near the arena in Aldlyn while Brad is in your party you unlock his brawling system where he can challenge a few people to a fist fight.
It's not in the game. The character was a a reward for a patreon pledge that was supposed to come later, but the person never fullfilled the promise. That's why I'm reluctant to continue with her events now.
