Required: Wire Rod, Flame Wand.

In the southwest corner of the map you'll find the graveyard. Examine your minimap and you'll see that one of the graves is not marked by a dot. The grave in question is one over (west) and three up (north) from the southeast corner of the graveyard. You can push this gravestone upwards to reveal a passage leading down. Talk to the Hero's ghost in the grave to receive the awesome Hero's Sword.