To me, an advanced soul is one who has overcome the grip of the lower mind. From the Christian/Catholic tradition, Saint Francis of Assisi comes to mind. From the Islamic Sufi tradition, Rumi and Hafiz. From India, figures like Ramakrishna Paramhamsa. There are many others including from the Jewish and Buddhist traditions.
Perhaps the best way to express it is to post a Rumi poem which I think really captures the point:
The Ascent of the Soul
I died as mineral and became a plant.
I died as plant and rose to animal.
I died as animal and I was man.
Why should I fear?
When was I less by dying?
Yet, once more, I shall die as man,
To soar with angels blessed.
But even from angelhood
I must pass on.
All except God doth perish.
When I sacrificed my angel soul,
I shall become what no mind e'er conceived.
Oh, let me not exist
For non-existence proclaim in organ tones,
"To Him we shall return."
I love this, truly. How you explained this...
An 'advanced soul.' I want this.