A few years ago I read this manga/manhua/webtoon about a boy who lived in a medieval era type setting with his father being a drunk blacksmith after his wife died, the son at the age of 12 goes to the ceremony for coming of age, during the ceremony he discovers that he has a very high aptitude but for will-grass (or something similar) and considered useless.
After going to a school and a professor saw his aptitude he secretly trained the boy and helped him become OP with monsters with rings colors.
Later in the story, it's revealed the son's aptitude is the same as his mother's and his father is a legendary blacksmith fighter.