It's a great story, what hits the most for me is how the passage of time is for Frieren. Even the heroes who defeated the demon lord turn from stories to myth and will be eventually forgotten.
I love how time moves super fast when we are watching from her perspective but is slower from fern or starks. It’s subtle but reminds us that she still doesn’t view time the same way that they do.
Yes I love how the magic in frieren works like it isn't just power blasting and glorious tool to fight but had so much essence to it like humankind magic being developed by flamme and difference kind of people invented their own magic that suits for their everyday life problem, also they're so much rules and mystery about other magic that aren't discovered yet or understand the principal behind it even for the main character..
Another impressive aspect of the world of Frieren is its self-consistency and the interconnected nature of the information we learn about it. As the show goes on, every new thing we learn fits perfectly with what we already knew, and not only that, frequently the new information allows us to look back on something we learned earlier and recontextualize it to learn even more about the world. To take one example (spoilers up to Episode 10), we learn in Episode 10 about Frieren's (originally Flamme's) trick of hiding her mana indefinitely, not for the purpose of hiding as demons do, but for deception, which is a really cool detail of the world's "magic system". But then we can think back to: Episode 1, where Fern is "practically invisible"; Episode 3, where Qual realized that the shield spell takes a lot of mana and tried to exhaust Fern's mana; Episodes 7 through 9, where all 4 demons (Draht, Linie, Lugner, and Aura) consistently underestimated Frieren and Fern, always felt assured of their victory, and commented multiple times about the heroes making tactical errors by using too much mana. And with the new info from Episode 10, we now see ALL of these events in a new light. But it doesn't stop there (spoilers up to Episode 19). Later (I forget which episode), we learn that Fern's mana control is something Heiter taught her after he noticed Frieren doing it, which once again recontextualizes that moment in Episode 1. Then, when we get to Episode 18, we are told that Frieren's mana looks like that of an "old mage", and that's WITH her hiding most of it, which further underscores just how much mana she truly has. And in Episode 19, we learn that she can completely hide her mana to the point where she becomes effectively invisible to mages and monsters alike. This is cool on its own, but it also once again recontextualizes every prior moment where Frieren's mana hiding has come into play, because we realize that every time, she wasn't just suppressing her mana as much as possible, she was choosing exactly how much to show or hide according to what served her purposes. For example, if she had showed up in front of Aura with too little mana, it would have been obvious to Aura that she was hiding the rest. She needed to show enough mana for "plausible deniability" to convince Aura that she was seeing Frieren's full mana. Episode 19 even has what seems like a simple transition scene of a stille landing about 3 feet from the exam proctor. But this is giving us a hint about something: either the proctor knows how to hide his mana, or he's using some other trick to get the stille to land there. Either way, it's telling us something new about the world in a 5 second cut-away shot with no dialogue. All of the above is just for the "worldbuilding arc" of mana hiding, and I didn't even cover everything there is to say about it. But there are probably a dozen other threads of world-building happening at the same time. The way show not only feeds you information about the world but also REWARDS you for remembering it later gets you so invested in learning everything you can about it.
It's not lacking, it's just a soft magic system. I'm not familiar with whatever Witchhat, but magic systems in fantasy run the spectrum of soft magic systems to hard magic systems. What differentiates the two is whether the magic system has strictly defined rules to it. Hard magic systems would be things like alchemy in Full Metal Alchemist or bending in Avatar. Brandon Sanderson's books all also use hard magic systems (in fact, that is his specialty). These systems have very strictly defined rules to how the magic works. We have a clear understanding of how the rules of magic works. Soft magic systems, on the other hand, have rules that are unknown to the viewer. Soft magic systems can and do have rules, but they are more nebulous to us viewers. We cannot know all of the rules of how the magic works. The magic in The Lord of the Rings and Harry Potter, and the Force in Star Wars are examples of soft magic systems. That doesn't mean that soft magic is bad - in fact, it can be used very effectively - but simply different. Again, this is a spectrum, so there are also systems that are sort of a hybrid or something in-between the two.