Unlimited Blade Works

Infinite Creation of Swords.
Though it is treated as a Noble Phantasm, technically speaking it is a type of magecraft called a reality marble.
Within this reality marble exists all the ingredients needed for the creation of swords. So long as Archer has seen the original, he is able to easily replicate it.
However, the replicated weapon has its rank reduced by one.
Replication of defensive armaments is also possible, but it requires two to three times more magical energy than a normal projection.
Once an armament has been replicated, it is registered inside the boundary field and can be manufactured with Gradation Air even without expanding the reality marble.
Against a normal opponent this is little more than a mildly annoying ability, but it is the natural enemy of a certain King of Heroes.

Fate/side material: Fate Encyclopedia

How many times have I’ve gone over this, Nausicaa?
This is Archer’s Noble Phantasm. It’s a barren wasteland with a thousand swords scattered about.
A great ritual deployed using eight lines of projection.
It’s a kind of old world magecraft known as a Reality Marble. A Reality Marble materializes the user’s inner world and overwrites the real world with it for a short period of time.
All the weapons that Archer can project are present in this space, and there is no need for him to project anything from scratch. He can immediately use any weapon that’s sticking in the ground.
In EXTRA, since the requirements for producing wrought iron have increased, Holy Sword class projections are possible (although their power is inferior to the originals).
…Well, what really happened is I took my eyes off the 3D art team for a second, and when I looked again I was surprised to find they had made an animation of “Excalibur Projection.” Since they put the effort in to make it, I figured might as well include it. As long as the Holy Swords are inferior to the originals I deemed them to be borderline safe as far as the lore goes.

Fate/EXTRA Material: Encyclopedia of Fate/EXTRA

Reality Marble, Infinite Creation of Swords.
A different world from this one, the imagined world that a man whose Origin became “Sword” due to certain circumstances reached. It was High-Thaumaturgy that the Shirou from this world originally couldn’t reach, but it became usable for a limited time after being corroded by the Heroic Spirit of a Card.
That imagined landscape is a snowy field in the dark night. Without stars or roads, and only just the crescent moon faintly illuminates Shirou. The innumerable stuck swords give the impression of the mountain of corpses that that Heroic Spirit saw. It’s a space supplied with every sword from every time and place, and swords come flying to Shirou’s hands, or to the enemy, the instant he wishes for it. That is faster than Projection by far, and it even outdoes the speed at which swords are produced from The King’s Treasure.
That said, because it is helpless against swords that don’t exist within the Bounded Field, regarding Ig-Alima and Sul-sagana he could project them superficially right after seeing them, and somehow managed to do it by hitting them and averting their trajectory. This cheat style… So you have received the protection of the Holy Grail, haven’t you?
The instant Miyu flew to another world, the mana path was cut off, and he became unable to maintain the Reality Marble. As a result he lost the battle, but the wish of the big brother who wagered his life was granted. By the way, at this time Miyu’s world and Illya’s world changed places together with the space of the Great Cavern, but there is the trick of Shirou and Angelica not being affected since they were within the Reality Marble. I hate how complicated this is.

PRISMA material/petit: Encyclopedia of Prisma Illya MOVIE