When you craft a pickaxe, it has a chance to be a failure, also known as "Duds". If you craft a dud, the game will say "Sorry, I crafted a dud! (P:*dud pickaxe power, Q:*dud pickaxe quality*, Dmg:*dud pickaxe damage*", in the text box.
The power, quality and damage will be random depending on your blacksmith upgrades.
They are very annoying and slow down progression a lot.
To avoid duds, try to upgrade blacksmith related upgrades if you have the money, as they can help to increase thing like pickaxe power that sometimes give you a higher chance to craft a proper pickaxe.