If she were an optimist, Leliana would conclude that the light is not covered in something that's probably terrible. However, the reality is that she is not an optimist and that they are in Kirkwall, a place famous for everything being three times worse than you anticipated, even when you were expecting everything to be awful.

In theory it would be advisable for the Advisor not to be the first to approach the inevitably terrible thing in Kirkwall. She did not come here, however, to send others to perform all risks. When she was in her tower she knew well enough that her agents were sent to do her bidding, to be her hands and eyes and ears. They performed their duty to help the Inquisition, and she would not act so high above them in the field when they relied upon one another for their lives and for the success of the mission.

She holds out a hand, cautioning, to stop any from attempting to pass her for a moment, and draws a pebble from her pocket, just in case, tossing it forward to see if the quiet clatter of sound or the bounce of pressure triggered any traps, or disturbed anything else that might waiting in the darkness near that light. Perhaps it would be nothing, but if something did react then it would not harm to have a little distance.