Fate/Stay Night Anime Saber's Avalon Sword

Saber:
She is Shirō's servant, an agile and powerful warrior. Saber is loyal, independent, and reserved; she appears cold, but is actually suppressing her emotions to focus on her goals. Her class is considered the "Most Outstanding", with excellent ratings in all categories. Because her master cannot effectively provide her with Mana, she minimizes her activity to preserve what she has. Saber is bewildered by Shirō's "protective" tendencies, and believes his erratic and reckless behavior jeopardize her chances of winning the Holy Grail War.

Avalon: The Everdistant Utopia
The hallowed scabbard of Excalibur, originally stolen from King Arthur shortly before the Battle of Camlann. Mere possession of this Noble Phantasm bequeaths limited immortality through regenerative stimulation, as well as preventing physical deterioration due to aging. When initiated as a Noble Phantasm, Avalon dissipates into countless particles and immerses its user into a tranquil domain, virtually a "portable fortress". While bounded in this manner, an individual is shielded from all destructive interference in the physical realm, from parallel worlds, and dimensional planes. Avalon transcends even the most advanced sorceries, and is comparable only to "true" magic. The name Avalon alludes to a legendary isle in English folklore, best known as the final resting place of King Arthur.