What are the chances a world filled with magic will develop similarly to earth. That truly depends on the people themselves and their choices as well as if the world actually flows in a similar passage of growth.

Well with this question I will say that the chances are very slim, the main difference is, you got it, magic.

As known, different worlds can possess vastly different ‘systems’ but the world we are speaking of is possible the closest to earth as magic gets.

It is called Urotrope and despite it’s strange name, it is a very earth-like world despite the magic, of course it isn’t 100% because it still adapted in it’s own way but that doesn’t really matter right now.

The story of this world was very much like any other typical magic world.

About a thousand years ago a Demon lord appeared and terrorized the world, wielding an infamous and deadly black sword simply called the Demon Lord’s Sword, he reigned over the demons, a collective group of humanoid beings.

In this world there are two ‘factions’ that have existed since the start of time known as Demons and Sentients.

Demons are both wild and racional humanoids and monsters of very magical origins and may have even been born from pure magic itself.

Sentients on the other hand are humanoids of mortal origins appearing through the process of evolution and some even from monster races.

As it was mentioned as well, the monster races aren't considered a faction because despite how powerful a monster can get, even a majestic dragon is only a ravaging animal.

Special things to know about monsters is that there is no special system that makes monsters evolve into some powerful race. Instead most monsters have bloodlines to which they grow in. Bloodlines usually involve special innate abilities and how the body of a monster will evolve as it absorbs enough mana to activate certain genes that are inactive in its early years.

Enough of that, back to the explanation. Originally the demon lord was a being who took control of the demons, who were actually not very active, in hopes to rule the world. The sentients and demons, besides a few individuals, did not usually war and many races were even peaceful until the appearance of the demon lord.

No one could topple the demon lord because no one possessed a weapon stronger than the demon lord’s sword. The Black blade, in this world, is considered the most powerful weapon in the world with even gods not possessing one because it isn’t a weapon that can be forged.

A Black blade can only be ‘bred’ and ‘raised’ from a sword of high enough quality and many unknown conditions.

Long ago not many people knew of this and in hopes of fighting off the demon lord, and restoring peace, a few special demons who did not like the reign of the demon lord stole an ancient magic he possessed which had allowed him to summon his infamous Demon generals and commanders.

These specific demons were also people who had come in contact with the demon sword during its forging but due to magic, they could not reveal its secrets.

Still, what they did do was craft the base of a sword that could eventually grow to rival the demon lord’s own sword and with that spell of summoning and the help of sages of many magical arts, they changed the spell to be able to summon a hero.

What they achieved was summoning three men at once.

The central one was the one which carried the bulk of the magic that reforged his body into one that could grow immensely, one had this magic reforged the power of his brain making him the most intelligent and the last was the weakest and was almost like a common human.

To the royalty they regarded only the one that could grow immensely and gave him the ‘hero’s sword’ and had him train to defeat the demon lord and his army.

What they never considered is that the summoning was always meant for a demon and not a human and that a human soul could not initially support the immense power of their bodies.

In fact, the soul of the hero had split in three with most of the soul in the hero's body, most of the intellect in the one with the reinforced brain and the smallest one actually contained his humanity.

The hero charged bravely into demons without a care for casualty while the one with the brain had immense talent as a mage and was recruited by the many mages to become a second hero who could become the most powerful sage that might even rival the demon lord in magical talent.

The last one was left alone due to his weakness but his kindness was the largest among the three. Initially having trained with the others he was still the weakest but with the skills and diligence he placed in his growth, he grew to have a great charisma that drew many people to his side where he founded the first Adventurers guild that worked to give jobs to vagabond travelling fighters and properly finding dangers in an area that can become the focus of adventurers to improve the safety of the land.

After killing the first demon commander, the hero returned with the hero's sword coated in the blood of demons. The holiness that countered the demonic energies of the demons bodies was almost exhausted by the venomous blood but the forgers did not worry as they took the sword and in magical flames in a forge specially built, they gathered blood of holy attribute monsters and forged a small amount of mithril of the elves into the sword.

This time the hero's sword had achieved the many hidden conditions of the means that the demon lord’s sword achieved and finally produced a spirit that would let it grow and restore its energies.

That said, many people began to worry about the hero and the archmage in training. Neither of them had any humanity and it was during this time that the three summoned met that everyone discovered that they were originally one person.

If they had stayed together from the start, after they had grown they would have naturally merged but each of them took a different path and formed different connections and now had different desires and none of them accepted to merge back into their original. Their souls would not accept it.

With time though, this became dangerous as they began to battle the demon army and pushing back in different forms while growing more powerful

The two stronger ones were on the brink of corruption of their egos when they themselves finally went after each other.

With their souls in three, even though it had grown immensely they were still a shattered soul. To maintain their existence they finally accepted the merge back into one and when they did this, the fame and legacy of the two merged once more back with the hero and this propelled the heroes sword to a whole new level.

That said within the merged body they were still three separate beings never fully merged, a trinity.

The new hero that came from the restored soul would also only move when the three came to an agreement or at least two out of three agreed.

That said, for some unknown reason, the part that made up their humanity had the most powerful part of the soul and in some subjects it was even impossible to move if not without his permission, mainly the biggest concern involving the hero and mage who did not care for life.

That said, even when they held back, the power was even more amplified as the power was forced into a smaller area or small section causing immense damage to more powerful enemies without causing damage to the land or the people near him.

Through the years of war, the heroes sword, despite being a sword originally white, grew through many different colors as it evolved and grew being coated in so much demon blood that it gained countless abilities that directly countered demons themselves becoming their bane.

When the last summoned demon general was killed, the sword had gone from it’s pure white to a ominous dark purple and it released a faint holy glow that was almost overshadowed by the constantly purple glow the sword naturally released.

With the demon army pushed to the brink, the demon lord himself appeared wielding his demon sword and against the hero, the two entered a war of one on one against each other.

That said, to the despair of the humans, the hero and the hero's sword, despite growing almost to the level of the demon lord’s sword, was still not its equal.

Throughout the battle the hero was battered and beaten until something happened when the demon lord, wanting to torment them attacked the humans of the nearest town which included the wife of the fragment that had founded the adventurers guild.

When that fragment realized that, something in the fragmented soul changed and the three fragments were suddenly merged with the main soul fragment being the most humane one who used his body to defend the humans but at the same time, his purple heroes sword evolved along with the hero himself.

Sentients are all said to originate from monsters and humans are one of the creatures with the most restrictive genetic evolution DNA. That said, when humans do surpass the need to evolve, it is said that they will ascend to possess so much power that it is said to have started to step into the realm of gods.

With a black sword in hand and two huge wings behind him, the hero stared at the demon lord who was now serious. The two just raised their weapons and flashed at each other. They came in contact with a world shattering explosion before a clear cracking sound from the source.

The power of the two collided and their swords shattered as they were the exact same in strength and exact opposite. As for the two holding it, they just stared at their enemy as their bodies vanished from the backlash of their power that their souls could not sustain.

This was the first known legend of the black blades that has been written in history of the world by the gods to never be forgotten by man or demon.

Still the hero was rewarded by the gods, the small humane piece of his soul that took control at the end and evolved, the gods found it in limbo as it travelled there and removing the great uncontrollable and corruptive power of the hero and gave just that piece a complete soul and a new normal body.

He was the only one who ‘could’ live normally and so he was given a new body that he could give birth to children and leave the legacy of the hero behind but this legacy was not one with the power of the hero but his humanity that strived for the good of the rest.

From that day the legend of the black blade remained greatly entrenched in history yet like always, few knew how to create the swords but those who obtain it know the conditions but to prevent another demon lord from appearing, the gods prohibit by the world laws the knowledge to be passed on to someone who did not possess a sword itself or who isn’t the disciple of those who know how to forge these swords. As such, the birth of a sword capable of becoming a black blade is left to the fate of the sword and it’s user.