@Samunth
And you aren't understanding, I'm thinking. Unless there are MASSIVE numbers of reincarnators, PEASANTS (who are told little to nothing) wouldn't know that not having the spot means no mana. One child in the village area (possibly ever) wouldn't make them automatically assume he had zero mana, especially since we haven't been told about a single way to test amount yet.
It would be too rare of an occurance for peasants to automatically know what it meant.
And even their magical cell phones wouldn't cover it. Its not like they could call up other kingdoms and ask. A peasant wouldn't know anyone to call that they've never met.
So your "it might be common knowledge" makes
no sense at all due to the lack of a way to spread information on such a small sample size to the far corners of a peasant village. 'Common knowledge' requires the knowledge to spread enough to become common.