Yamashita_Kaito
You should be very carefull which position should be considered “good” for noblemen to send their heirs or other sons. If you wish to create a full world politics are part of it and places where noblemen mingle are important. As an adopted son our protagonist is considered noble, while the rulling king is in opposition he should not be officially against it as it umdermines his authority as well. Some nobles will still be in favor of Zak as he is the former king and should have some loyal followers despite stepping down. You can later create a backstory fand “academy arc” if you wish to with some intrigue, power play between the highborns and adventures, also some skills and abilities learned by our hero. Oh and smiths are usually lean and with high endurance and not muscular, bulky and “strong” as strongman athletes.