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