After a couple of rounds of intense battle in various positions, Damien already confirmed that his soul cultivation also improved as he circulated the Eternal Bond of Sacred Hearts.
He was pleased that he could use his dual cultivation art to improve his soul cultivation and not only his ethereal cultivation.
At least, he didn't have to worry about hunting for herbs with spiritual essence or absorb the soul essences of others unless needed.
The former required him to wander into dangerous territories, while the latter option was one he found useful only when he killed his enemies. It was not as if he always had people to kill, nor did he want to kill needlessly.
Of course, these two options were just the fastest way to develop one's soul cultivation. There were other ways, one of them involving just simple mediation only but took more time relatively.