Resolved KN Action novel about a dude who goes into another world once in a while.

Uhh, I don't remember much except the fact that the MC was the successor to this clan that is full of knights and warriors. He doesn't have much talent in sword skills though. He's very well-versed in fighting. He goes into the body of another dude whom I don't remember the name in a different world where the development of magic is much more advanced. He learns skills from the dude and then I think he taught the dude in exchange for learning magic the skills of his house.

 

2000 years of magic history in my head

 

That's it. Thanksssss