Originally called the jagehakkei, its blade is seeping with poison, and is able to bring down even giants [sic] monsters with the smallest of scratches. It's [sic] name seemingly having no meaning, though various theories have been passed around over the years, this blade is still surrounded in mystery.
Yakei is a high-ranked katana that requires the Katana 3 license to equip, and provides 74 Attack, 5 Evade, 29 CT, 13% Combo Rate, and a 10% chance to inflict Poison when attacking with it. It can be bought for 12,500 gil at Balfonheim Port or dropped from any of the Baknamy at the Nabreus Deadlands (1% chance).
In the Zodiac versions, it now provides 83 Attack, 27 Evade, 31 CT, 20% Combo Rate, and a 10% chance to inflict Poison on a target and requires the Katana 4 license for 90 LP. It can be bought for 9,300 gil at Archades and Balfonheim Port, dropped from Baknamy at Nabreus Deadlands (1% chance), and found as treasure at Tchita Uplands (The Lost Way), Necrohol of Nabudis (Cloister of Distant Song) ad in Trial Mode Stage 89 with the Diamond Armlet equipped.
Yakei is a Katana obtained by finding and turning in the Flamering Key found at Snowy Woods. It provides 58 ATK and has a 30% chance of inflicting Poison.
Yakei is "fowl," "night view" or "night watchman" in Japanese.