Kirkwall's Circle has a long history of madness and death. Even the soporati who should be immune to such effects frequently report feeling as if someone is watching over their shoulder. The Knight-Commander of the Templars of the Kirkwall Circle appears to have been a bit hrm, overzealous even before she got her hands on a cursed object. Southern Templars can repel magic.

If the city itself is a glyph channeling magic, it would keep the area unsettled. And I don't just mean rumors. There are verifiable patterns that far more mages go bad and far more murders happen in Kirkwall than is normal.