In addition, some weapons are only available once per playthrough or require laborious farming. The upgrade material for fire and lightning weapons is expensive and rare at least until the Lord Vessel unlocks new world areas. There is an opportunity to make very powerful fire and lightning weapons for any type of build, and most importantly, for use in early-game. The only requirement is the ability to wield the item successfully.
These deal the same amount of damage regardless of your build. That is not the case with Fire and Lightning weapons. A strong magic build will deal more damage with an enchanted sword, while a melee build with high STR will deal more damage with a large sword or hammer. Weapons that deal normal, divine or magic damage scale on a specific stat (STR, DEX, INT, FAI). It characterizes and guides your build and upgrade progression.
In Dark Souls, your weapon is your single most important possession.