The April Fools Weapons are the untiered weapons that drop from Null in The Machine dungeon, released in Patch X.31.5.0 (Apr 2019).
The Machine was originally conceived to be only for the April Fools event, meaning these weapons were limited availability, however the dungeon was later made a permanent rare godlands drop from the Steel Construct.
Each weapon is an in-joke about something connected to Deca’s User-Generated Content or members of the UGC team:
Mister Mango: references an unused bag sprite that resembled a mango.
Butter Bow: references Toastrz, a member of UGC.
K.I.D.D. Force: references Kiddforce, a member of UGC, and the redesign of the Lost Halls which is a UGC dungeon.
Caduceus of Current Craziness: references Atrapper, a member of UGC.
MMace MMurderer: references MMoas, a member of UGC.
Blade of Ages: references Xaklor, a member of UGC.
The weapons are 
soulbound.
Unlike some groups of similarly themed items, these weapons have greatly different fame and feed powers:
Mister Mango: 1% fame, 833 fp
Butter Bow: 5% fame, 777 fp
K.I.D.D. Force: 5% fame, 20 fp
Caduceus of Current Craziness: 2% fame, 35 fp
MMace MMurderer: 1% fame, 1313 fp
Blade of Ages: 2% fame, 202 fp
