From Leveling Up the Hero to Leveling Up a Nation

It feels like I (27 y/o) who specialized in [Training] skill was no longer necessary for the Hero’s party which has grown stronger for a certain degree. At first, I was the center of the party but in the end, the hero dismissed me from the party. However, because I have Made a great contribution to the party until now, I received a small Fief instead of retirement money. As my heart felt the loneliness of leaving the adventures front-line and heading to my territory, I thought something after seeing the seven villages with their 2500 population. My thoughts are the following… I wonder if I train these people, won’t my territory become strong enough that could even defeat the demon lord?