question for our experts: Archer vs. Gilgamesh in UBW

The key-like sword (which is the Noble Phantasm itself, not the vault) to enter the golden capital of Gilgamesh. It opens a portal in space that allows him to take out the items inside as he pleases. Goes without saying that the more wealth he has, the stronger a Noble Phantasm this is. Weapons in it can be thrown out like projectiles or taken out normally. Strictly speaking, the weapons inside it aren't Noble Phantasms but the prototypes of them, or one way of putting it, nameless/fameless Noble Phantasms. The most dangerous thing for other Servants though is as Gilgamesh has most of the weapons that became Noble Phantasms in his vault, most often he'll have a weapon that had been their weakness when they have been alive.
Rank: E-A++ (of course Ea is also in the Gate so technically he does have one EX weapon in it)
Type: Anti-personnel

Treated like a Noble Phantasm, but to be accurate, it's thaumaturgy. Able to use a Reality Marble, with no penalties. Exactly what are those penalties? Who knows.

In this Reality Marble, the substances needed to form all swords are present. Just by looking at the original, it is possible to replicate it. However, the replicated weapon is lowered by one rank. Defensive armaments are possible but the normal projection cost is two to three times the regular amount of Prana used in making swords. A weapon replicated once is recorded in the barrier and can be made without activating the Reality Marble using tracing thaumaturgy.

Against a normal opponent, it's only an ability that's somewhat troublesome, but it's the ultimate counter against a certain king of heroes.

The substances involved in the creation of Ea are probably not inside it; Ea wasn't possible to analyze. Creation of Excalibur is possible, but not a perfect version of it. It's also likely that using its energy blast would result in him using up all of his Prana, hence it would be a suicide attack for him, which is why he never traces it even just as a normal weapon; his personally developed close-combat technique with his twin swords is better suited for him and Shirou (although raw power might be less).

For Emiya Shirou, whose life had been saved by a sword and who actually merged together and lived with a sword, his body wouldn't be the type that would destroy itself from sword-making.