Fragarach

The ultimate form of counterattack, an unavoidable strike carried out in response to an enemy’s strongest ability. It both kills the enemy and nullifies their attack, creating a perfect balance between offensive and defensive capabilities. However, it a far less convenient weapon than it sounds. It can only be used at full potential against an enemy’s most powerful strike, otherwise its power is reduced to that of a mere Rank D attack. Like Gáe Bolg, Fragarach operates by manipulating causality to rearrange the order of attacks, placing the always fatal strike of Fragarach just before the enemy's attack would be launched, paradoxically eliminating the enemy and their attack.

Bazett can only create ten of those per year by pouring her blood on them and letting them charge for a whole month. During Fate/hollow ataraxia she only has three shots remaining.

Its greatest weakness is revealed against enemies with the ability of self-resurrection, such as Berserker, or those with powers similar to those of Fragarach, such as Lancer's Gáe Bolg - Impaling Barbed Death, which pierces the target’s heart before the attack is even carried out. In the case of Berserker getting hit with Fragarach, he would lose one life unconditionally, seeing that God Hand is always active, while in the case of Lancer's Gáe Bolg, both Lancer and Bazett would be killed, as both attacks are unavoidable.

As rare an occurrence as it may be, Fragarach is indeed a Noble Phantasm wielded by a living human. It is one of the few remaining relics not yet attached to a Heroic Spirit.

Based on the magical sword from Irish mythology, said to be forged by the gods. Also known as Answerer (That Which Comes Later Cuts First) or The Retaliator, it passed through the hands of more than one hero, including Cú Chulainn.