All sword should be free and each sword can obtain by different task
Only some sword cant be free such as: Tanjiro sword, Yoriichi and Kokushibo, because those breathing are rare.
Next, should be added more location for upper rank demon fight (NPC). Moreover, there should be different biome in the game and the flame trainer should be rengoku dad.
Lastly there should add water breathing dead claim. you can go to find giyu at lv 300 for the skill.
this all is my idea :)