In my opinion, it's not worth burdening the main hero with this skill. If it's really necessary, it's better to develop the secondary character's intelligence so that, after interacting with the main hero, he can pass on his valuable knowledge to the people.
Are you sure that a secondary hero has enough intelligence to learn the knowledge of your main hero and pass it on to the people?
So you fall at his feet hes the one who betrays you
Its the servants devotion for the decay
Stand up
There are no flowers on your grave
There are no chains
There I keep chanting for the forgotten name © Amorphis