@Glomoro:
There's always something that
can go wrong, but I'd have ranked assassination here as extremely dangerous—at the very least, we know something is wrong with the protagonist's soul (that seems to be a moral peril), that even the highest of high priests can't necessarily sort out, and for which we have reason to believe the assassination target may have some answers. By contrast, there's no specific reason to believe that she's difficult to lock up (other than her generally being a wildcard, which is a problem in all scenarios). Waiting around gathering more info does indeed have its own risks, I wasn't necessarily advocating for that (from a pure risk-management viewpoint, anyway).
...Does the duke know all that about the souls and whatnot, actually? I can't remember if that was made clear at this point. If he isn't fully up-to-date on the fact that Beatrice is potentially a lead for the soul problem, then maybe it isn't so foolish of him after all.