I was wondering, since people with enough Breaths for Fourth Heightening can feel people around them with breaths, and better the more breaths they have (That's what I understood anyway) but can't sense drabs...
That leads me to believe that they can sense the investiture in a person(?), so I'm wondering if they would be able to sense a surgebinder holding stormlight, or even infused spheres, based on their life-sense.