User blog comment:SayuriDarling/Full first chapter of The Mark of Athena/@comment-4430596-20120901173341

I think the Mark of Athena is most likley something that gives Annabeth some type of power. Think about it, Jason can call down lightning and fly, Percy can make hurricanes, control water and a bunch of other awesome things, Piper can charmspeak, Leo can controll fire, Hazel can control valuble metals, and Frank can shaapeshift. What can Annabeth do? I know she is smart, but so is Frank, they don't really need another strategist. So, knowing this, I have to conclude that the Mark gives her a power to rival the other six.

(I'm assuming Annabeth is the 7th for the sake of disscusion.)