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 "fowl," "night view" or "night watchman" in Japanese.