The hero needs a weapon. Maybe his ancestral sword was broken by the villain and needs to be repaired. Or maybe the weapon he has just isn't good enough. At any rate, he needs, not just any sword, but the right sword.
And the right sword must be custom forged.
Thus, we get a Forging Scene. A skilled blacksmith, perhaps even a magical smith or the hero himself will take molten iron (Thunderbolt or [...] [tvtropes.org]