Demonite Bar

A bar and the ore inside it fetch the same at a shop, so melting a stack purely to sell it buys you nothing but time at the furnace. Smelt what you intend to build with and leave the rest sitting as Demonite Ore.

Corruption ore is rationed by how many orbs you can find and how much patience you have for the Eater of Worlds, and the temptation is to pour all of it into weapons. The Nightmare Pickaxe is the piece that actually moves the run forward, since it is what finally lets you cut hellstone out of the underworld and everything good down there follows from that. Lights Bane can wait a night. The pick cannot.