BTW, this chick is also some goddess of war that went through a lot, as the author reminds her from the days he was playing as an Otaku. Her eyes were filled with sadness as she remembered her adoptive parents being slaughtered by the necromancers's skeletons. In this world the protagonist wasn't capable of saving her adoptive parents and she cried her crocodile tears for about three paragraphs, and then she moved on. Shortly after she followed behind the protagonist that was as nimble as a cat because of his training with a shadow class player in his former world, while caring a few tens of kilograms through a dense forest in a dense night. I don't know, maybe she has some goddess skill, like pinpointing the protagonist d*ck smell and following like a beast in heat.

Okay so we find out he’s not so useless after all. His abilities are just locked.

And MC did not defeat him like in typical xianxias where MC surpasses the god's level and becomes ultimate being with no rivals, but because main enemy did not know everything as he thought

Well, there is couple of characters that author introduced but never developed but they are minority and more like 3 or 4 characters

This story seems to be a mix of Chinese, Japanese, Western and even Korean elements. Although the equipment system is a little confusing, if you reread it a little bit it becomes much more understandable. I cant say that the characters are unique either, but the action in the story is very good.

The world the MC is in has a form of magic knight system where a person trains, then when they reach a certain level of strength (gold), they have a chance of awakening their element. There are also of course mages and other classes, but most common is elemental knights. The strength of people is measured by multiple ranks of metals like iron, silver, gold and etc.

The MC is a Plainswalker, or to be more accurate a plainswalker candidate. Plainswalkers are pretty much demigods who can traverse different realms and can alter reality to their own choosing. 8/10 most powerful people you hear about in history in this novel were plainswalkers.

The MCs gaming system is NOT something that actually exists. When the MC most likely awakened his memories from his previous life (we don't know yet but MC sees himself as Brendel more than Sofie so his original self still seems to be there). He interpreted the world around him as a game he played, so his plainwalker power is to turn reality into a game. That power is unique to only him, and no other plainswalker should have it (Each plainswalker has their own unique power/trait on top of the cards). So him getting XP, classes, items, learning skills and judging people of this world by level is all his plainswalker power altering reality.

Other than their unique trait, the universal way for plainswalkers to grow stronger is through cards. Which is based on Magic The Gathering. But you don't need to know the game to enjoy it. Just understand that the most important cards are land cards. They are like building your own realm and the larger your realm, the more creature cards or spell cards you can have/use.

At this point in time, he has went from plainswalker candidate to plainswalker apprentice. So he is still not a true plainswalker just yet. Probably because he still has not made his own deck. Though there might be other conditions. A true plainswalker can summon entire armies without lifting a finger. But at the moment, the MC simply has a few cards that he is barely able to maintain. As he grows stronger or gets more land cards, he can summon more.

Taking a guess about the game system, the MC having terrible luck with items but one of his summons having good luck is all a figment of MCs imagination. Aka, more than likely if he were a true plainswalker he can get any item he wants. But that shouldn't be confused with getting a legendary item of a weak goblin. The potential has to exist in the first place. This is why he is able to get a ton of XP shaving off some ancient power that he found. Think of it like equal exchange.

So to summarize, there is only 1 power that MC has, the plainswalker power. The game system is a trait of his plainswalker power and he is able to use the magic system in this world through his game powers.

UPDATE 7/21: We now have a bit more information about plainswalkers as MC has become an actual plainswalker. Him being able to use most cards was a privilege as an apprentice. Once you become a plainswalker, you gotta choose your own path and build your own deck. Which means you can only keep some of the cards (amount of cards he can keep is based on his total mana pool) and the others would have to be thrown away (Don't worry, MC will keep most of the cards we are used to him using). And those cards he does keep are upgraded/changed.

One thing that does make the MC special is he is a double plainswalker. Aka, he has both the mana pools of Brendel and Sofie.
Going into wild guesses territory (I can be totally wrong) Sofie's trait as a plainswalker is the game system, and Brendel's trait is Sofie (directly or indirectly, aka the trait can be more than just that)

The main girl Romaine is actually a timid person who would rarely do anything rash. To put it simply, you know those people who would cause a mess and do crazy stuff when their parents/sibling is around, but are completely to themselves when they aren't? That is Romaine. She acts like that because she knows Brendel will somehow make it work out. This is probably because her Aunt is a witch who was most likely a quite powerful person who gave off similar feel. We don't know how powerful, but the queen of the witches was on the level of a plainswalker despite not being one.

As for the "rival", he isn't that significant of a character. He does show up later on with side characters but he isn't negative towards the MC after he gets hit awake (yes, characters actually learn here)