Something was clouding the future, and the order's very connection to the Force was weakening. That a Sith Lord existed somewhere in the galaxy, was not in doubt but could this shadowy villain really bring this much imbalance to the Force?
Interesting that this quote links the weakening of the Jedi's perception to the imbalance of the Force. Kind of backing up what Borb was saying.
The second installment of a two-part article by Abel G. Pena entitled “Aliens in the Empire†mentions that the dark side adept and future Imperial Procurator of Justice Hethrir “possessed Darth Sidious’ rare talent to cast a dark side shadow over Force users, dulling their abilities.â€
And this one suggests that its a unique property (similar to other unique properties seen in such as teh Exile, Cade Skywalker, Zayne Carrick etc) rather than through sheer strength in the Force.
Thanks for the ammunition Gid! he