In the new story there are specific enchantments or weapons that are classed on how much damage they can deal to demons
Unique items, weapons or enchantments have a few that are strong against demons

S-rank : Exorcism - Rare and extremely powerful enchantment similar to purge, its powers are so extreme that it can end up killing humans as well, this is a last resort and is only given to extremely strong or powerful elites ranking within the top hundred strongest in the world... although powerful like purge its effectiveness is all in how it is used

A-Rank : Purge - A unique enchantment and sometimes also made into the form of a material or poison. This is said to completely wipe out a demon's powers. It will defeat even the strongest of demons if it hits them enough times, while it kills weak demons against demons with unique abilities it is not a guaranteed kill so its effectiveness is up to the user

B-Rank : Demonbane - A special material that hinders demon regeneration and in general will kill most C-Rank and lower demons, but not the best idea for use against ArchDemons and Overlords

C-Rank : Enchanted Weapons or items have the strength to defeat most normal demons and is rather useful in general

D-Rank : Any normal weapon or item can be useful against normal demons but in general takes specific attacks or a lot of attacks to be effective

Currently the hero just has a sword, and you must not forget they also have the power to use magic as well so it not like these items are the only methods