I don't know if we just have to wait for more articles (or the full rulebook itself) to ask these kinds of things, but here goes a question anyway:

I know what the little shields on the top left of the artwork do on some cards (you can discard that card to prevent damage equal to the number of shields) but what about that blue dot that is right above the faction icon on some cards?

You can see one here right above the faction icon on the Leman Russ tank:

And there's one above the faction icon of the Alpha Legion Infiltrators for Chaos:

The Drop Pod Assault card has both shields AND the blue dot (it looks a little like a targeting reticule):

But the Daring Assault Squad has no such icon:

I'm hoping it's similar to the shield icon except you can discard it for +1 ATK or something similar.

Anyone know? Or want to share in speculation?

Loyal units that cannot be used by other factions. They're mentioned on the support page for the game. It's in the same spot but a different colour than the yellow symbol for the cards that come with a Warlord.

Ah great! Thanks! I hadn't seen that yet. I like this a lot better than adding another keyword like "Loyal" to the keyword line.