Before setting sail, Lady of Mist, Laila, had warned Amberser that the goddesses he had offended had once again united to cause trouble.
So, after confirming that these monsters were tracking him, he instantly understood that it was Shael's doing, or at least she was one of them.
After having received knowledge of the Dark Web from Shael, Amberser could be located by this Dark Goddess at any time. That was the price for acquiring forbidden knowledge, which was why, after he had tricked Shael last time, he didn't even return the Divine Artifact dagger to her. Since he could be located anyway, having one more Divine Artifact made no difference.
Now, seeing Shael's smug look, Amberser wasn't much bothered, these goddesses talked big, but in reality, they always ended up delivering.
The main reason was that these goddesses were always scheming against each other.