Shingan no Yuusha - Vol. 1 Ch. 5 - Vampires of the Ancient City

[daimaouanos]

It is not making sense how everyone can tell when the ability to analyze other people's abilities is being used... The Goddess hasn't chosen them and it wouldn't make any sense for the goddess to just give out information about her ability that she grants her followers. So how does everybody know?

Maybe, just like how you feel someone staring at you in the real world. Plus his eye glows, as Miria mentioned back when he was analyzing the baby.