Abadom
Some advice, many of the chapters felt off and amateurish (no offense) and I couldnt find out why until I realized, the transitions in between words, sentences, and actions could do better. Vocabulary could be updated, and some sentence structure is redundant like 'it is' which could be effectively shortened or just changed in general
So it seems there is a higher chance of MC spending less time in a world that doesn’t have the right factors to maximize skill growth. Meaning this world has some limits on physical enhancements (assuming you don’t go for some top tier cybernetics, nano machines and such). But getting such enhancements would be risky as they could easily interfere when he gets back to reality (assuming they would carry over). So will he be able to stay longer after the mission completion or just head back? Would it even be worthwhile to stay here an extended amount if he can? He probably won’t stay even if he can due to the uncertainty of whether the time difference is negligible or not. Needs to use this as another sample to more safely determine whether he can expect future classes to have a short time away no matter how long he subjectively stays. In any case, the Trait Sword Heart is a must to carry over to the main class. While it is subtle it should have great effects.
Author, I think it would be pretty neat if the MC went to a world like persona. This is because persona are the manifestation of the user's psyche(like his mind stats). This would give the MC's mind stat more use in battles plus a persona would augment the user's physical abilities. Hence, this allow the MC to give a boost to all of his stats due to his increase mind stat plus the MC can pick up resistances to certain elements.