The guy already has knowledge about the melidians and still awakens a meridian martial spirit, this is like giving wings to a tiger, it would have been much better if he had no knowledge about it at all, and then he would develop the techniques more slowly, because from 175 onwards, the guy is already super OP
The only flaws for me are, 1. he started with a technique from his past life, since anyone else wouldn't have it, 2. he compressed his soul power so much that he was forced to absorb the power of several soul beasts. 4.8
The only thing I didn't like was the MC using a technique from his past life, since someone else in his place would have either burned or succumbed to the evil fire.