Kaido mention that he sensed Oden in the blade.
What Enma does is written on the page you just ignored. It creates EXCESSIVE DAMAGE by using up the weilders haki without his permission
That’s all that ever been stated it does and that’s all that has ever been SHOWN it does. It takes you haki without permission and does excessive damage with it
Nothing in the story has said “it stores haki”. That’s YOUR HEAD CANON