Ugggggggggg....
It's ok to have the MC have more knowledge than the average person, or even the average swordfighter. But I mean really!? The natives should have a grasp of basic tactics at least.
Take the wolf for example. He easily dodged the attack and 1 shot it. Lets just assume that a crit is a x10 multiplier. Here's the thing, he has bad equipment and is low level. So someone with decent equipment and a slightly higher level should be able to do significantly more damage than that. So a normal person that doesn't know how to crit could still likely 2 shot the wolf, or even 1 shot it with a skill. So that wolf shouldn't be more than E tier tops (assuming a novice could be expected to beat F tier).
And even if you ignore that, his attack was from dodging on reaction and stabbing it in a specific spot. The specific spot can be chocked up to special knowledge, but his reaction time cannot be. Remember, he explicitly has a bellow average reaction speed. Even with a new body it's not going to be THAT much better than the average person.
So if he could easily reaction dodge the wolf, then someone else with a few battles fought already should be able to do the same. Meaning they could just do that 10 times and kill the wolf with the same equipment, levels ect.
And that sword fight, it's not rocket science that you should exploit openings whenever possible. And a pro swordfighter ought to be in the habit of minimizing time spent vulnerable and maximizing odds of landing a strike. But lets ignore all of that for a second, the MC hit him anyways and crits. 1 shot and he's down already. Isn't that a bit silly? Again, even if we assume 10x crit damage (remember, most games use 2x) levels and equipment in MMO's are a big deal. Even a few levels can make a gigantic difference in damage vs defense. So a swordsman being hit with a level 1 crit, while he might be surprised by the damage, should still be able to tank it no problem.
Is the crit multiplier really just that insane? Is it also true damage or something? Who tf designs a game like that! And if crits are so integral to the game, then it should be obvious that they exist to the natives to the point where all of their martial arts should be warped by them.