"It isn't a trait only for that group. It is a shared trait between the 3 groups that separates the ignorant from the intellectuals."
This is where your definition of agnosticism is wrong.
This isn't a "trait" that is "shared" by agnostics, it is agnosticism. Re-read that dictionary definition. Agnosticism isn't a 'third group', it's something that is shared between both theists and atheists - and which, as you say, separates the ignorant from the sensible.
"As long as you say this then you are an atheist. No agnostic could say this and be considered agnostic."
Why is it okay for an agnostic to say they believe the supernatural exists, but not for an agnostic to say they believe the supernatural doesn't exist?
"Saying this makes you non ignorant but still an atheist nonetheless."
It makes me an atheist who is also agnostic. Again, check the dictionary definition of agnosticism: it means no more and no less than the acceptance of the limits of human knowledge. This is something that both atheists and theists can do.