Diatrekhōn Astēr Lonkhē

is Achilles's given to him by his father , and previously given to Peleus as a wedding gift by Chiron. He cannot invoke the True Name against female opponents due to carrying an awful amount of regret from killing the Amazon Queen Penthesilea with this spear.
Differing from that of Karna's spear meant to bring about destruction with immense weight, it is a simple spear with sturdy workmanship that is well designed for close combat. Pierce the chests of heroes, he holds it lightly in one hand as a means of using for its original purpose as a throwing weapon. Having been able to pierce through all other heroes, he feels it is superior to any other weapon in the aspect of its thrust, allowing it to pierce hearts and penetrate skulls with every strike he makes.
When summoned as a Lancer, this spear would also gain abilities similar to Gáe Buidhe, in which wounds inflicted by this spear cannot be healed as long as it exists. He doesn’t have his chariot in the Lancer class, but he can wield this spear with divine speed while dashing around the battlefield on his feet for mobility, so he is an unmanageable threat in either class.
In Fate/Grand Order, it is treated as a Skill in gameplay.
===Duel Field===
During his life, he developed an ability with the spear that not even Chiron knew of, using magecraft to create a , a fair battleground between two opponents, where no gods, outside help or elements of luck can intervene. It creates an arena cut off from all of the surrounding environment and time, which isn’t released until one of the combatants is defeated. In terms of magical theory, it is virtually the same as Aestus Domus Aurea. It is a separate dimension outside of time that is comparable to a Reality Marble, so when the duel within concludes, it will have lasted only a second from an outside perspective. Due to Hector not wishing to fight Achilles with the advantage of his immortality, he developed the ability so that they could evenly fight. 
However, his spear can only be used against “those who Achilles wants to fight one-on-one against”. In other words, if Achilles doesn’t “wish to fight them” and the opponent doesn’t have enough courage and skill to respond to his challenge either, Achilles won’t use this spear. Furthermore, even if Achilles himself wants to fight them, he won’t try to forcefully bring his opponents into the one-on-one arena if they don’t want to. It is a Noble Phantasm with a narrow range of enemies it can be used against. While the fight against Chiron in Fate/Apocrypha involves only fists, weapon usage can be permitted. Achilles must descend his chariot to make this Noble Phantasm function usable. And due to the nature of this Noble Phantasm and the curse by the Amazonian Queen, it can neither be used on someone weaker than himself or on a female. The three people that Achilles never wants to have a rematch with regardless whether it is before or after his death are Hector, Penthesilea and Chiron.
In the manga adaptation the Duel Field creates a colosseum, rather than the color-changing visual effect of the anime.Fate/Apocrypha Chapter 56: Diatrekhōn Astēr Lonkhē
==Development==
In the original light novel of Fate/Apocrypha, the design for the spear was incomplete and it wasn't fully seen until the anime adaptation. The spear bears a teal tip and rings upon its handle in ' adaptation of the Fate/Apocrypha anime.
-ディアトレコーン・アステール (Ancient Greek: διατρέχων αστήρ , Greek: Diatrekhon Aster ) An ancient Greek word meaning "shooting star."
-ロンケーイ(Ancient Greek: λόγχη , Greek: Lonkhe ) An ancient Greek word meaning "spear."
ディアトレコーン ・ アステール ・ ロンケーイ = ΔΙΑΤΡΕΧΩΝ ἈΣΤΗΡ ΛΟΓΧΗ = διατρέχων ἀστήρ λόγχη = Diatrekhōn Astēr Logkhē = Meteor Spear.
(A strict transliteration renders Diatrekhōn Astēr Logkhē. A representation of how it would be said yields Diatrekhōn Astēr Lonkhē, because that's what happens with gammas and velars in Ancient Greek. Perhaps even Loĝkhē if you're feeling adventurous. If one uses Lonkhē, you can see how it led to the Latin lancea, and thence to English lance. Diatrekhōn is literally to do with running, as befits Akhilleus, but there's no way to make Star-Running-Across Spear sound natural in English, or like it means a celestial body instead of an athlete).
==References==
vi:
Category:Noble Phantasms
Category:Anti-Unit Noble Phantasms
Category:B rank Noble Phantasms
Category:Spears
Category:Bounded Fields similar to Reality Marbles
Category:Reality Marbles
Category:Noble Phantasms introduced in Fate/Apocrypha
Category:Noble Phantasms of Achilles
Category:Spells