Theres two version of the wep.
14* D Rekusion(Rod)
Im sorry I dont know the english name of the rod but thats what the JP wiki says after google translate. The sword can easily be found by hunting Ill Gills on Infinity rank Mission(level 205-250 I think). I suggest doing MAI 4 Infinity rank for this(its where I got my
ones). The rod can easily be found by doing MAI 1 Infinity rank. The rod is a boss drop.
Theres many other way you can get both version of the blue scythe but I'm just suggesting how I got both versions. Hope this helps.