All-Black

As all of this was going on in Halycon, Asgard received an unwelcome guest. A guest who had a very powerful weapon. John actually didn't fear the guy but that sword that he wielded.

The sword had a very terrifying reputation. It's name was even known to the Gods and the Celestials even fought against the actual owner of the sword.

Knull.

This All-Black sword or the Necrosword was essentially the first symbiote. Yes, the same species where Venom came from. The All-Black was manifested from the shadow of the evil deity Knull and tempered using the divine power of a slain Celestial. Primarily taking the form of a sword made from living darkness, All-Black was wielded by Knull during the dark god's deicidal rampage, earning it the monikers of the Necrosword and Godslayer.

Knull was the deity who belonged to the darkness from which the The Celestials made the different universes from. Knull didn't like that another party had come to his home and made his peaceful home dirty.

Knull, felt by creating universes the Celestials soiled his home and thus attacked the Celestials, even though he was defeated by the Celestials, he was able to kill some of the Celestials.

Knull knew that he wouldn't be able to kill the Celestials easily, so he created the Necro Sword. The first symbiote. When Knull made the sword he had to use a hammer striking at it. The hammer strike produced massive sound and the forge produced heat for its shaping purpose.

And from that point on sound and heat became the main weakness of the first symbiote and this trend continued to all of it's later generations. It was for this reason that Venom and all other symbiotes had weakness against sound and heat.

And of course even after making the sword, Knull was defeated again and decapitated (not killed). After that battle the sword escaped. Since the sword was a symbiote it was able to travel in space easily.

And after years of searching for a good host, he finally found one who was worthy of his host.

Gorr, the God butcher.

Gorr was a normal guy who lived on a very barren planet where their species used to go through hardships everyday just to survive. They lived a nomadic life and deaths due to hunger, hunted by animals, lack of water made their lives more harsh and cruel.

But even after all of this they worshipped Gods. They believed that Gods would make their life easier. Gorr too believed in the beginning but as he lost his parents, his pregnant wife he lost faith in Gods.

He was denounced from his clan for losing faith in Gods and was banished into the wilds alone. But destiny had other things saved for him. After twists and turns, The All-Black fell into his hands.

And since being the first symbiote, the sword had tremendous influence on Gorr, making him go into rampage against Gods. Gorr vowed to purify the universes from all Gods and hunted Gods actively everywhere in the Universe.

In the actual story, Gorr was defeated by three Thor. Yes, three Thor.

One from the past, one from the present and one from the future. It took a whole lot of power to bring Gorr down. And even then he later got resurrected from the All-Black which had previously escaped in the battle.

And now Asgard was visited by the same Gorr, well at least a version of Gorr in this universe. When John first saw the images and the sword, All-Black was what came to his mind. And since it was All-Black, it was probably Gorr since he was the second owner of the sword.

Truth to be told, John was scared at the beginning. If it was the actual Necrosword it would have been a very tough battle as it was one the top 5 weapons in the universe and might have needed all the forces together to defeat Gorr, but the moment Gorr landed with his spaceship on Asgard, John felt relieved.

Because with the help of Nabu and his magic, John was sure it wasn't the actual Necrosword. Though the sword had the same kind of power, the power of darkness, it wasn't so overwhelming that John would get serious about it.

"What's wrong with this sword? Isn't this the All-Black?" John mumbled.

"I have a feeling that this sword is just an imitation of All-Black. Not the actual Necrosword." Nabu gave his own thoughts. As they were conversing in John's head, Gorr finally stepped down from the spaceship with which he came here.

The spaceship was huge but it was piloted by him alone while he searched for Gods all over the universe. When he heard of Asgard he immediately steered his ship to its location.

The sword always followed him, but surprisingly it seemed agitated the moment he stepped at Asgard. It was as if the sword was afraid of something.