Enkidu (Noble Phantasm)

Enkidu is the Noble Phantasm favoured by Gilgamesh. It is a chain used to hold the "bull of heaven" that brought seven years of famine in Uruk, and is a Noble Phantasm that Gilgamesh trusts more than Ea.

It holds the power of "commanding to gods". It grows stronger as the target has more divinity, and thus is one of the few anti-divine weapons. To a target that has no divinity, it is no more than a solid chain.

Source: the dictionary resource at Jonnobi.

It is actually spelled "Erukidu" in the game, but this is heavily suspected to be an evident typo from Enkidu, who was the only friend Gilgamesh considered to be his equal in the Epic of Gilgamesh.

In the game, it is used in the UBW route). Gilgamesh first uses it to restrain [[Berserker (Fate/stay night)|Berserker, then uses it to grab on Emiya Shirou to escape the Grail. It is also seen again in Fate/hollow ataraxia.