Gan Jiang and Mo Ye [Noble Phantasms]
Kansho-Byakuya.
The Yin-Yang paired swords which Archer favoured.
The swords forged by the famed swords smith Kansho of Wu, during the Spring Autumn period of China.
Kansho received orders from the King of Wu to forge the imperial sword, however, he could not think of ways to forge swords that fit such orders. He was really frustrated and desperate.
Seeing this situation, his wife Byakuya decided to gamble her own life.
In order to forge items reaching the realm of Gods, sacrificing of human lives is absolutely necessary.
Thus Byakua hurled herself into the furnace in front of the husband she loved, using her own life to help the Essence of Five Mountains and the Metal of Six Heroes meld.
Kansho forged the two swords in grief.
These are Kansho and Byakuya, a pair of twin swords that reflect Yin and Yang.
Since they were forged with the best materials and human life, their abilities as swords are great. In addition, they also have aspects as magical weapons used in Witchcraft and Rituals.
It is unknown why Archer chose to carve what seems to be spells of warding all over the swords."
- Fate/side material - Gan Jiang and Mo Ye