Giving you all Details
I do not like to do this type of chapters, not anymore. Due to readers always misunderstanding or not knowing lore I have already stopped responding in NovelPhoenix, I am hopefully doing this chapter to clear the doubts and not let the same things happen.
I will give some references as the proof, if you do not care to search then it's not my problem, you are free to drop this fanfic.
Magic Stones: They are essentially heart of monsters.
First Point: Monsters do not vanish instantly(Reference to the Volume 1, chapter 2 or 3 depending on translation of Bell taking out a magic stone from a kobold's corpse), unless their magic stone is directly destroyed in a battle(Reference to Bell defeating Mutated Goliath in Season 1)
Second Point: Dungeon actively absorbs corpses so in dungeon any monster will rot very quickly as compared to the outside world. However for collecting Magic Stones we have Supporters(Lili as a prime example of taking out magic stone out of Killer Ants for Bell).
Third Point: If Magic lingers in any part of the body of a monster even after their magic stone is destroyed during battle or taken out of their corpse later on, that part still remains in the world. It is usually hide, claw, tooth etc which is called item drop. (Reference to Bell getting item drop from his fight with Mutated Minotaur in season 1 which he uses to craft second dragger which is blood red, I forgot the name of it. But apparently that got destroyed in his second fight or first fight with Xenos Asterius in Season 3 as far as I remember)
Fourth Point: Monsters outside of Orario and dungeon have interbreed and their magic stones are much smaller, that means in any battle chances of destroying their magic stone is less, the value of their stone is also less so it's usually not worth taking out for strong adventurers, letting the corpses rot(Not by low level surface adventurers), and in this era all Orario entrances are not sealed so magic stones are still pretty valuable as they are usually hybrid of dungeon monsters and surface monster bred over the recent years.
Fifth Point: Ember in this fanfic clearly had a hoard of magic stones that he sold to acquire money for his magic grimoire purchase. This is why his solo runs never exposed his prowess as all monsters vanished or rotted after he took out their magic stones.
Magic Grimoire
The prices were cheaper than in Orario, because Orario usually imports them from other places and they are auctioned at inflated prices, it also considered that we are not during canon, adventurers in Orario rn, such as Hera and Zeus Familia are still stronger than Loki Familia, however they have not reached the peak of Level 8 and 9 in their current generation but we have more people capable people alive rn.
Falna
Idk who was arguing it in the comments but yes if a God dies, then the adventurers falna is sealed and they are reduced to basic human level.(Reference to Sword Oratario Volume 7, if you want direct proof, reference to the Sword Oratario Manga Chapter 61, Panel 20-30)
(There is another proof in Volume 11 of Sword Oratario, Or Manga Chapter 108, which clearly shows Familia members losing their falna. I do not wanna spoil which God died or what happened, but you can go there to see it)
All of this is Canon, these are side-stories that show Loki Familia's point of view and what was happening simultaneously while Bell was in Rookie games. Bell Cranel also helps during this portion of story but I am not going to spoil that.
Ryuu Lion's falna is still there because Goddess Astrea is still alive however she now lives outside of Orario(That is why Ryuu still has her abilities), as a proof please refer to the Great War between Hestia and Freya Familia in later seasons or volumes.
The only thing Ryuu was unable to do was get any more stronger as she was not meeting Astrea and able to update her Falna.
Also if a God dies and person has their status sealed, their falna isn't reset. If they find another God. They can unlock their status and regain all their abilities.
That is why Ember was relaxed because if Aurora had died then his falna would have been sealed and he would have lost all his superhuman powers including his endurance and magic(He could still use innate magic).
Secondly this portion also confronts to the geography of this world
NOTICE: THIS IS A VERY SIMPLIFIED MAP OF THE DANMACHI WORLD, HOWEVER GENERAL DIRECTIONS OR THE AREAS WHERE THESE MENTIONED COUNTRIES ARE SUPPOSED TO BE IS MOSTLY CORRECT, THIS WAS THE ONLY HIGH DEFINITION MAP EASILY AVAILABLE SO I AM USING THIS. HOWEVER PLEASE NOTE NOT ALL PLACES ARE MENTIONED HERE SUCH AS ALTENA SO REMEMBER WORLD IS A WHOLE LOT BIGGER THAN SHOWN IN THIS MAP.
Anyway Karuna City is closer to the EMPIRE, as I have mentioned before. It is also close to Alf's Royal Forest or Wishe Forest depending on the version of map you are going with(That is why Ember feared his identity getting exposed) There is a lot of space between between Alf's Forest and Beol Mountains, around there Argon Town is located, and in even a safer spot Shawn Village is located.
I am not good in directions such as North, Sout, East or West, but I do generally tell where the place is located and if it's in the official Danmachi Map, I mention direction briefly.
Anyways, that is why there is an influx of monsters such as monster stampedes(I have mentioned in Winter Hunter and later chaps that beast horde was primarily coming from direction of Orario).
Now, Ember remembered Behemoth getting killed in Dedine Desert. So his thinking was, if he runs towards it(No Survival).
Runs opposite(Alf's forest and shit had locked on him for some reason).
If he goes to basically west(Idk if I am really getting this direction right, correct me if I am wrong), there are towns and cities located(However to reach Argon Town or even Shawn Village, it will have to go through major cities, and a portion of Alf's Forest as well) depending how it goes.
Secondly Ember does notices it has wounds that means some familia, extremely strong one is probably fighting it, Idk if I had uploaded that chap yet or not(Probably not), but to not spoil it. Like canon it will be pushed to Dedine Desert, away from Alf's forest and all cities and towns that come before Argon Town and Shawn Village and later die in the very same desert.
We do not know the entire events from novel on how everything went but I incorporated a version if it, and events of my story align as best it can with all limited information we have on the world.
I really love discussing with readers, but I do not have unlimited time for all questions. Please atleast search it on your own before asking anything. If you do not find the information you can ask me it is AU, or I have taken it from some sort of media.
Due to repeated harassments from readers on WN, who do not know lore, or even fucking read the fanfic properly I have stopped responding there.
They always not read properly then blame me or insult me for not agreeing with their point(When point is on fanfic I have fucking written)
Do not make me do it here, if push comes to shove I will stop responding here as well. However serious readers can still join my discord and ask lore questions in appropriate channels which I will be happy to reply.
Invite: Xb47VnFUpQ)