This has been puzzling me for the past few weeks of 1840. There have been any number of instances where one would think Gerard would have the ability to discern the truth about situations beyond an ordinary mortal's capacity, yet he hasn't displayed many powers other than giving Daphne bad dreams with his Celtic cross ... (e.g., he's unaware of Gabriel sneaking up behind him in an attempt on his life).
If it's the case of choosing to exercise his powers or not, Judah has had a seemingly curious lack of interest in using them ...
Another factor that I thought of was love. The mere fact that he fell in love with Daphne (or at least claims he was in love) could have put a damper on his powers in the same way that Nicholas Blair faltered when he fell for Maggie.
Beyond the fact that there would not be much of a story if Judah's powers were all-powerful
Couldn't it be Gerard, and not Judah, who falls in love with Daphne? Considering how evil he is, is Judah even capable of loving anyone? Ultimately, it could be the power of Gerard's love and contrition that weaken Judah's powers and resolve.