Slightly easy fix for that: Have him lie about his age. Kids who want to be taken seriously will definitely pretend they're older, and you don't have to go with a prodigy angle if you're already coming from a line of high-quality smiths. Learning how to do something from a pro is going to give you insight and technique that you won't get otherwise. I imagine growing up in a celebrity chef's kitchen produces a better chef than someone who attends a community cooking class, you know?
He could be a believable sixteen year old, lying about being nineteen. Working an anvil would give him more musculature than someone his age would "normally" have to help lend credence to his sneakiness.
He could be a believable sixteen year old, lying about being nineteen. Working an anvil would give him more musculature than someone his age would "normally" have to help lend credence to his sneakiness.