Crystal Nightmare chest loot. Like all Crystal Nightmare loots, this can also be found in the chests at the end of the boss run.
Also a Lapis Ruins relatively rare chest loot.
Additional Notes[]
With good ATK and moderate benefit to DEF and MDEF, this can be considered quite a good weapon, however its only known location make it somewhat less desirable than stronger or more easily attained weapons.
Rusty Dagger • 
Crafter's Knife • 
Thief's Knife • 
Survival Knife • 
Pure Edge • 
The Sculptor • 
Tuna Shanker • 
Twisted Blade • 
Atou • 
Dragon Fang • 
Ghostblade • 
Assassin Blade • 
Cultist Dagger • 
Master's Dagger