Shirou got the blades removed at a remote clinic and then threw himself into the practice of projection magecraft until his circuits were pushed to their limits. Normally magus doesn't approve of this practice as the pain and results are not proportional but kiritsugu encouraged this.
He did so because even if Emiya Crest handled the process of using time to alter the burden of the flow of mana would fall on Shirou's circuits. after all, it doesn't matter how much downscaling had been done by the creator, the origin of this spell is based on a grand magecraft that usually drains 1st class magus dry when not powered by leylines.
Shirou slowly got acquainted with this form of training, magic circuits are like metaphysical muscles. They slowly grow with use and enter a stable output of energy, also like muscles if you don't use them they will get atrophied like patients after waking up from years of bed rest.
Then they can be trained too like muscles can be trained by pumping iron and maintaining a diet. magic circuits can also be trained to increase their maximum capacity and output but like musculature`s limit depends on genetics the maximum possible output depends on the innate potential of the mage which is linked to the pedigree.
(A/N: and using a similar muscle reference, sorcery traits are like genetic mutation, especially the trait Blue Blood: Noble magic circuits of the Barthelmoi family id like having the mutation of muscular hypertrophy as an inheritable trait.)
He also found out one of the minor reasons why magi specialise in one magecraft. it is because of how the muscle structure of sprinters, marathon runners, swimmers and weight lifters are different in structure similarly practising the same magecraft can make your circuits in that and make it very easy to cast that form of magecraft.
Shirou also learnt as much as possible about magic capacity and circuits from the book that he had his father buy from Melvin while he slowly got used to feeling soreness from his whole body due to his increased physical training and the magic circuits.
He decided to practise the basic mana manipulation more as it was hinted that being completely filled also helps in the growth of magic circuits. Once he completely depleted his body of all the od it naturally takes a long time to fill again hence he is aiming to practise mana manipulation to learn to consciously pull in mana from the surroundings to fill his reserves.
2 weeks passed by like this. After making another scrap in the shape of a sword shirou went to bed to give the well-deserved rest to his weary body and soul. But after he fell asleep he awakened in the familiar void making him sigh.
As he prepared himself for another vision showcasing his doom his gaze cleared but instead of being above fuyuki or even being in his body, he saw kush forests and a huge field. The trees were unknown to him. The forest had 40-meter-tall trees that were thick enough for 4 adults to hug them.
And what off-put him was this was supposed to be the peripheral shrubs of the forest, not the wilds proper. His vision slowly zoomed into the field and he found that there was a clearing in the middle of the wheat field.
The clearing was scattered with training tools like wooden swords and training dummies made up of straw and wood. There were also various other weapons made up of wood and some poles clad in armour placed in a formation likely trying to imitate a formation.
Shirou is confused and dumbfounded by this scene as it is like an ancient training yard instead of any place in the current timeline. Looking at the middle-aged implements scattered around shirou guessed that he might be having a vision of the past instead of the future.
While contemplating he saw a head full of shining blond hair walk into the fields. It was a child about 5 years older than him. He was dressed in coarse black clothes that looked like they had not been dyed at all, he looked like how people would imagine farmers from the middle ages.
The child went to the weapon rack with practised ease and picked up a sword then took a stance in front of a wooden dummy and began striking it. He practised this monotonous movement for what felt like hours and when the sun climbed to its peak his momentum was interrupted when a light brown-haired handsome young man walked into the clearing through the singular path.
The young man was wearing clothes that were a little better than the younger boy but what took attention was a sword that hung from his waist and the leather armour that he wore. The armour was bordered by some kind of fur. He said
"Brother come here and eat lunch"
While pointing at the bag in his hands. The two brothers pulled out a straw mat from behind the training rack and sat down on it. In the anime of lunch, they had black bread and water, the younger boy was happily eating the black bread with such gusto that it made shirou question his knowledge that black bread tasted disgusting.
He watched the brothers spar and tried to memorise the stances and movements as he had concluded that he needed to learn as many sword styles as possible. He had an idea of learning multiple styles to one day create his personal style that complemented his magecraft and guns perfectly when he refined all 3 skills.
Shirou watched as the boy trained all day and then near evening went inside a stable and meticulously took care of the horses. The horses were larger and ferocious looking with bulging muscles and long manes. He brushed them thoroughly and trimmed their hooves then provided them with enough feed in the form of grass and some grains and buckets of water.
Looking at the child sleeping in the stable Shirou's vision twisted and turned as he was back in the void and then slowly the orange void also disappeared as well letting him have his well-deserved rest as he fell soundly asleep.
.
.
….
Shirou woke up still contemplating the vision of the past, he woke up and took 4 different vials of drugs. 3 of them are for preparing his body for the next part of the emiya crest he would receive next week. The last one is the Miller family supplements that kiritsugu finally made a contract to deliver supplements every month and become a regular customer.
Shirou`s forging was also quickly catching up in his smithing training as he began trying to forge blades and it's only been a few months since he had begun his apprenticeship in forging. Well, most of the blades were scraps but with the help of structural grasp, he was able to modify them at the speeds unfathomable.
This method gave results but it was very draining for his mana and put a burden on his mind. Shirou noticed that the amount of data obtained from structural grasp is steadily increasing from just the shape and form at the beginning of practice he can now finely create a mental image and measure the size as well as composition and the object it it is a blade.
The deep analysis takes about 1 minute of complete focus but shirou is now able to project knives indistinguishable from the original in shape size texture or even smell but he had a creeping feeling that the insides are hollow, even when he copied the material in projection by using his magic circuits to aid his calculation abilities the performance of the projection was weaker than the real knife.
Looking at this kiritsugu stopped instructing the boy in all forms of common magecraft as he thought
Now I will only aim to teach him all the basic magecraft he needs and then practise survival techniques.> . . . …. Rin and shirou sat side by side beside a tree Rin`s left arm had a fresh red bruise and Shirou's clothes had dirt and mud as he had been blown off by the pressure wave Rin released. The winner of the day`s match was shirou as one of the bullets he fired while being blown hit Rin in the neck and for a real combat situation, it would have been fatal. Rin said "So you are constantly training your circuits to increase the capacity and need an idea of what to do when you can't use magecraft and also don't want to waste mana by simply releasing it." (A/N: we have the Garden of Avalon in the visions triggered by Clarent. And what do you think of the explanation of magic circuits, did I miss anything? . . . . . THANKS FOR READING:)