Noble Phantasm

Noble Phantasms (宝具) are "crystallized mysteries", armaments made using the imagination of humans as their core, and weapons or abilities owned by Heroic Spirits. They are the embodiment of the ultimate mysteries of a hero that symbolizes his existence through historical facts and anecdotes. They can be general weapons, such as swords, lances, and bows, or support items, such as rings and crowns. They can also be abstract concepts, like abilities, curses, and changes to the environment and its physical properties. Noble Phantasms are considered to be a Servant's trump card and are activated by channeling prana into them and releasing their true names. This can only be done by their true owners.

Noble Phantasms far outrank other non-legendary items, meaning that a C ranked Noble Phantasm is the equivalent to an A or A+ ranked normal attack. Rin provides several examples of a Noble Phantasm's power; dragon-slaying swords, shoes that can run far and wide, god-killing demonic swords, and Hazanken, a weapon in Chinese legends that can only be swung once, but is said to be able to even slice through mountains. There are cases where the nature of the Noble Phantasm is not actually a true crystallized mystery, such as Archer's Unlimited Blade Works, which is magecraft that symbolizes him, and Li Shu Wen's No Second Strike, which is the quintessence of his martial arts. Sasaki Kojirou is a case of a Heroic Spirit without a Noble Phantasm due to his status as a wraith, but his technique, Tsubame Gaeshi, has managed to be on par with Noble Phantasms without the use of magecraft.

Noble Phantasms are generally based off of previous incarnations of weapons, and with each cycle of transmigration a weapon undergoes, it becomes weaker. If faced with their predecessors, newer incarnations will generally lose during a confrontation. The current number of existing Noble Phantasms is very small, but they still exist in the material world. The only use of a Noble Phantasm in the modern age is Fragarach owned by Bazett Fraga McRemitz. The reason it can be used by a normal human is the members of her bloodline are "Tradition Carriers", who have the ability to reenact the powers of old due to the blessings of their god. Avalon, recovered by the von Einzbern family, also still exists as a Noble Phantasm. It lacks ability without a connection to Saber, but it still exists in pristine condition after one thousand five hundred years.

It is possible to sacrifice a Noble Phantasm for an attack that is one rank higher, which is called a Broken Phantasm. If a Noble Phantasm is packed with prana, it can be made to explode after striking its target. It is nearly impossible to repair a destroyed Noble Phantasm, and as they are the trump cards of Heroic Spirits, they are unlikely to take such measures. Archer is a special case, as he can reproduce as many copies of Noble Phantasms as his prana will allow due to Tracing, allowing him to also counterbalance the fact that all of his projections are lowered by one rank. If a Servant wishes to destroy their own weapon in another fashion, it is much easier than destroying one in normal combat. Lancer is able to easily break Gae Buidhe in half without any effort.

Classification
Noble Phantasms are classified by their effectiveness against enemies.
 * Anti-Unit Noble Phantasm (対人宝具) - Anti-Unit Noble Phantasms are those specialized against defeating other people in single combat. Compared to stronger weapons, they will not go beyond defeating other beings no matter how strong the magical energy or curse they wield. Saber's Invisible Air wouldn't increase the speed of an action like chopping wood, and Lancer's Gae Bolg, which strikes the opponent's heart, would just be a strong lance if the target is a rock or a house. The advantage over stronger weapons is that they can be compared to guns with unlimited ammo while Anti-Army Noble Phantasms are one-time missiles. Missiles are more powerful, but an Anti-Unit can be continuous like Invisible Air. There are also those that are very cost effective like Gae Bolg, so it can be called a sure-hit arrow that is better at killing single people than a cannonball.
 * Anti-Army Noble Phantasm (対軍宝具) - Anti-Army Noble Phantasms are those with a wide enough range to be specialized against armies. They are more powerful weapons than Anti-Unit Noble Phantasms, capable of easily blowing them away, but they must be used more wisely because of their larger cost. Using an A rank Noble Phantasm takes a great deal of prana, so they must wait before they can use it again.
 * Anti-Fortress Noble Phantasm (対城宝具) - This rank has powerful Noble Phantasms that can even blow away solid fortified structures. While the difference between Anti-Unit and Anti-Army is the variation in area of effect, Anti-Fortress Noble Phantasms are distinguished from other categories by the great difference in power. Only Excalibur has this rank in all of the Noble Phantasms of the Fourth and Fifth Holy Grail Wars.
 * Anti-Army, Anti-Country Noble Phantasm (対軍、対国宝具) - The classification of Brahmastra belongs to this rank, but the difference in power from Anti-Army is not elaborated.
 * Anti-World Noble Phantasm (対界宝具) - The classification of Enuma Elish belongs to this rank. While the actual output is around the level of Excalibur, its effect that is unquestionably that of the legend of "ripping the world" puts the sword in a special category.
 * Anti-Thaumaturgy Noble Phantasm (対魔術宝具) - The classification of Rule Breaker belongs to this rank.
 * Barrier Noble Phantasm (結界宝具) - Noble Phantasms used to create barriers belong to this rank, but it does not include those that are also used to attack. Avalon is purely defensive, so it is a typical example of a barrier. While other Noble Phantasms like Blood Fort Andromeda may create barriers, they will instead be classified by their ability to attack like Blood Fort Andromeda belonging to the Anti-Army category.