Waaaay back before the Bronze Age, there is no evidence of butter implements being used. However, we are sure that the cavemen used butter knives of a rudimentary design. Unfortunately for archaeologists, global warming of the earth over the past few thousand years has caused all ancient butter knives to melt. All that is left are a few knife-shaped grease stains. I wish people would stop warming thier bloody globals, it's causing untold damage.
We do know that the Neanderthals used butter spears to kill their prey, and butter arrows and quivers were used in the middle ages. Evidence for this has been found in the European Butter Mountains.
Take some fresh dairy butter and sharpen the butter until razor sharp. Keep in the fridge.