Not really sure what the spoiler policy on BBS is as it's been out for some time but spoilers below.

 

So I just played Birth by Sleep Final Mix on 2.5 and Ventus' visit to Radiant Garden gave me some questions. How does Even know that Ven's heart is pure light? The only people who know this before TVA go on their journeys are Master Xehanort and Eraqus. So with that in mind, wouldn't Even have to be told this information by one of those two? And if Master Xehanort did share that with the apprentices, that just opens up more questions.

Even... Ven... omg Ventus confirmed as one of the 13 Darknesses

 

No but seriously, I think it was just meant to display his keen powers of scientific observation.

He's a scientist studying the nature of hearts, I don't see why he would't have such an ability

He's a scientist! Observing things is what he does. Yes

I just thought it was odd for him to say something, as we haven't really seen him with keen senses like that. I mean, Zexion was the one who thought Riku's scent was Xemnas' in Chain of Memories. So I guess Even can do it too, it just wasn't flat out stated.