The magic of a returner in the manhwa and anime is very special. It usually comes with hidden powers and unique traits that drive the plot forward and make the character stand out. Also, it might have some rules and limitations that add to the complexity and excitement.
The specialness of a returner's magic lies in its rarity and the way it gives the character an edge in various situations. It might have unexpected effects or be tied to a profound backstory.
The weakest colorful magic treasure in a chivalrous man's dream was the Thousand Mile River and Mountain Painting. According to the description in document [1], the main effect of the Thousand Miles River-Mountain Painting was the speed boost, not the damage output effect. Its damage was caused by the movement path, not the type of damage that was actively fired. Therefore, when fighting against Daemon Kings and desolate beasts, the Qian-Li River-Mountain Qian-Kun Painting had almost no damage output. It was only useful against small monsters. Therefore, it could be said that the Qian-Li River-Mountain Painting was one of the weakest colorful magic treasures in a chivalrous man's dream.
Well, without having read the 'inferior magic swordsman novel' specifically, it's hard to say for certain. But generally, in a novel with such a title, we might expect to see a story centered on a magic swordsman who is at a disadvantage in some way. It could be that his magic swords are of inferior quality, or his skills are not up to par with the other swordsmen in his world. The plot could involve him trying to improve his situation, perhaps by seeking out better weapons or training. There could also be elements of adventure as he travels to different places in search of ways to enhance his abilities, and he may encounter various challenges and enemies along the way.
Well, it could be that the magic chocolate in the manhwa is a key element that leads to adventures or solves problems. Maybe it grants wishes or unlocks hidden abilities.