The Dead Men Tell No Tales Curse was a curse placed on several locations around the realm during the time of The Hermes Seal.
Background
The Hermes Seal, enacted around 1000 PR, meant that most, if not all, murdered creatures would come back to the realm as a ghost, which could then be communicated with if there was some sort of supernatural or spirtual caster on the scene.
About
Because places like Nymphsview were steeped in illegal and nefarious activity, it was typical that they would not want any victims or witnesses to be able to speak from beyond the grave now that it was such an easy task to find and talk to ghosts. As a result, a form of dark magic was spread through the whispers of the realm, and a number of locations both large and small became subjected to this mostly-harmless curse.
If a ghost is summoned in an area of the curse, it appears as a static, emotionless spectre. It's the equivalent of "Hold Person" but for a ghost. As a result, trying to get testimonies or stories out of the departed became nearly impossible, though some spirit wardens and supernatural casters were able to push their prophetic powers to the brink in order to overcome the curse and temporarily break it during times of extreme duress or need.