My idea is based off of the form of how you weild the blade it gets evolved and stronger the more u train if that makes sense 
How it would work:
You start with a flimsy kinda starter form of a demon slayer then after awhile of training (maybe a form training exercise) u start to develop a more skill full form and whenever u use a breathing skill u would start with a perfect stance?
I will put an image of the breathing first attack being more skilled kinda