The {Black Dragon of Crimson Sky} was a sword technique of pure aggression, meant to take advantage of the user's overwhelming strength to deal even more damage and cause more destruction.
Since it was unique to Cain, it employed two sources of energy; his Ki and Demon Matter.
Although Demon Matter did manifest physically, Ki was more of an energy source than anything else.
Demon Matter was meant to empower his attacks through the blade itself while his Ki could extended beyond his blade to create energy attacks. But that didn't mean his Demon Matter was completely bound to his blade.
No, such was far from the truth.
The nature of Demon Matter was devouring. It was fundamentally a twisted source of energy that could profane other forms of energy and turn them into Demon Matter.
It had done this to the Devil Essence within Cain's body, turning it all into Demon Matter.
That was how it behaved within him.
