In 'light' of this conversation, I thought I would chime in. Jean said something that has me thinking. Now, this is just speculation, so don't ask me for a historical reference. I will put forth a modern tactical point instead...
I've been in the military (active and reserve) and in law enforcement for 21 years now. I've trained and been part of countless night operations. I won't talk about blackout drive or night vision, but I will raise a point. A few years ago, Surefire introduced a model of tactical mounted pistol light for just this purpose. The main flashlight has a pair of low output colored LEDs called 'nav lights' mounted below the main bezel. These lights are to be used to negotiate terrain / obstacles during night operations in situations where a bright white light would ruin your night vision of give away your position. We do the same thing with small helmet red/blue LEDs in the Army. They only provide a few feet of illumination, but in total darkness when your eyes have adjusted, these small colored LEDs provide great lighting to move, see, and read by. And, best of all, they are attached to your weapon.
It's possible that the lantern
shields could be used to dazzle an opponent, but I believe that this would be a secondary goal - as engaging an enemy would probably put out the light. Swing around a candle or small oil lamp in one of these, and I could almost promise that it would blow out immediately.
The primary goal seems like it would simply be a tactical device readily available to see in the dark - probably invented by town guards and adopted for other uses by civilian and criminal elements.