While I am of the opinion that some characters need nerfing, I do not believe Tirarian is one of those characters.
She has 3ish main skills, speech, alchemy, and marksmanship. In order to use her crossbow, I assume she needs to rather meticulously set it up, like the medieval variant of a modern day sniper, and she has what I'm guessing is a modest skill in close combat with her sword. That sounds fair to me. She's an alchemist, which I'm guessing is her main skill, since she grew up with it. And dealing with criminals may involve some amount of tact.
If you were really desperate to nerf your character, I'd say tone down the alchemy a bit, since Tirarian was thrown out at age 10, and therefore only had a few years with actual, dedicated alchemy training, while the other years were more experimental in nature