Alex watched the Elder die from start to finish. He had every instinct in him telling him to run now that he had the chance, but seeing the killer of his friend die before him was not a moment he wanted to skip out on.
He felt a cathartic sense of relief when he saw her head fly off and no soul escape from her body. But, he wasn't sure if that necessarily meant that she was truly dead.
When a Saint died, his soul came out of his body disoriented, not knowing what was happening to it. Most of the time, the intelligence in that soul was a simple one, meant to only save the soul in the moment when the body had died.
Those sorts of souls never knew that danger could be lurking outside and that they shouldn't come out.
However, Immortal souls were much more intelligent. Not only were they intelligent, but they also held memories and personalities, which made them no different than the person they were before, just without a body.