A: The only indicator of Shadow/Light use is that actual physical effect of that power. Other Shadow Touched can't sense it, and neither can Sunkissed. Some aren't even outwardly detectable, save for the supernatural effect that they might have. For example, Leap is - for all intents and purposes - mostly lacking in physical effect. The product of that effect, however, is quite obviously not normal. Auspex is another power that has little in the way of visual or physical indicator, and is difficult to detect.