There is only one way to obtain a mining weapon.
Mining Axe is only available when completing all Missions from NPC missions in the temple,
Once you came to last task and you get it done, reward will be Mining Axe !
Stones are spawning around the city every 6 hours, there's total 4 of them.
While Mining Stone there's chance to broke the stone, once it's broken, its gone.
Once you sucess in Mining you will receive 5x Pieces of Royal Steel.
Once you collect enough Royal Steel, visit NPC Budex Crafter +1 Temple
Budex Weapons are the strongest weapons in-game and they are not obtainable through shop.