(I thought of how to explain the nerf in Mimirsen's physique and I have got the best explanation. Just remember he is like 18-20 in age, while Thor in his 500s looked like a 10-year-old Midgardian)
'An acolyte, without the robes though. The numbers of chains are enough for his eligibility for graduation, and no robes mean he is newly graduated from Citadel, without joining the order of the Maesters.' The Maester's chains were apparent, but wearing no robe meant he had let the order of the Maester.
Jim still needed someone for the mass production of Wildfire. With the reserves of fossil fuels not mentioned in the story, it would be a pain to search for them, and then all the mining and processing is not worth it, while Wildfire is a feasible replacement for him.
Qyburn had mentioned he could produce Wildfyre in small amounts, but he needed large quantities and Qyburn served different uses for Mimirsen.
"Hey, man on the black horse, come here for a moment."
The horse turned around with a neigh. "Where do you hail from, young man?"
"Dorne." The voice replied with pride and arrogance.
"You have graduated from Citadel?"
"Does it matter?"
"Yes, it does. I am in need of a Maester." Mimirsen sounded all lordly to the Acolyte to accept his proposition meekly, as he did with Qyburn earlier.
"I have no silver chain." saying this the man reigned the horse hard, leaving the site without speaking further.
Silver chain served for the medical capabilities of maester, so Mimirsen came to the conclusion that the man thought that he needed a Maesgter for treatment.
"That was weird. He did not even listen to me." Mimirsen contended his options. His horse could have hosted both Qyburn and him, but that would have been a very uncomfortable proposition.
Qyburn was to leave from a ship to the North while selling the horse, which Jim had bought from the Reach. The horse would have not fared well in the North.
There were not many bandit groups here south of Westerlands, so he could not just raid them for immediate money and transportation.
"Well, I finally have the chance to try to tap into the Bifrost. There is no link in this world from where The Bifrost may arise like there was on the edge of Asgard, but it would not hurt to try."
"I had it postponed as Worst case scenario, in which I can't control it and it goes rogue. Destroying this planet, but now I have some unfounded confidence out of nowhere ."
"As far as I have observed the Bifrost, it has always needed a weapon, serving as its key for its summoning and control. Odin had Gungir, Heimdal had the sword Hofund, and Thor had the destiny to wield the Stormbreaker in the stories. While my Weapon was never mentioned, and my father was used as Weapon.The mind of Mimir."
"I wanted to continue using some kind of spear as the ALLFATHER sign, like that of Odin, the Gungir. It looks majestic. While in private, I need a sword or something like that for duels and tourneys, if I would be participating."
"But do I need to fight?"
In Asgard, when a child is 25 years old, i.e. comes of age, he or she receives a talent from the ALLFATHER. The ones who receive the Talent in arms join the army or the Valkryie depending on their gender. The ones who receive the talent in magic, become witches or wizards.
Some rare individuals develop their talents adequately, evolving them into their own divinity. These get to serve the crown more closely to the throne, potentially having the prospect of marrying into the royal line.
Mimirsen was a very special case. He was to receive his talent like any other at age 25, like Thor did, receiving the fighting talent and then somehow developing it into his divinity of Thunder at the age of 297.
However, Mimirsen Jim gained, not evolved his divinity at the age of 9, which was unprecedented, disqualifying him from getting any talent as he had already gained its evolution. And the divinity of wisdom did not help him in fighting in any form.
At his current age of 19, he should have been in a cradle, like the other 19-year-old infant Asgardians, however, his body matured very rapidly after the gain of divinity.
It was Mimir who had to stop his aging somehow, otherwise, he would have looked older than Odin at 40, which was no good for the young kid.
He did slow down the process, but the harm was already done, making young Jim look like a man in his 20s while his peer children were learning how to crawl. He already looked of similar age to Thor and Loki who were in their 1400s, while having the same fighting prowess of that as that of a kid Asgardian.
This could have been a traumatic experience for any other, being an alone child in the world of adults, but Jim handled it moderately with constant help and support from his cousin Odin and his nephews.
But his growth was to remain stunted, for then and forever. Unlimited stamina and above-average power for a Midgardian.
He could defeat Mike Tyson or any strong Midgardian in a long fight, but the threats in Asgard were not at Mike Tyson's level.
Jim remained in deep thought for some time when he saw the black horsemen return on the horizon, with an old man in grey robes following him on another Dornish Sand steed.