I recently made an axe model, animated it swinging, then applied a Idle npc animation to it. That didnt work so how else would I make this swing back and forth?
Maybe a motor6d with its value being changed in a while loop to make it rock back and forth?
Have you tried looking into bodythrusts?
It mentioned in the roblox developer hub that you can use BodyThrusts to apply a torque (Rotational force) onto parts
(link to page)