Ok, so I've got my design done. It is a cup-shaped, closed, white angelica with heart-shaped leaves, intertwined with a tubelike, open, white aloe with a square stem. My Estate is epiphany, and its sanctity is my highest bond. Next to that is the Catholic Church. Angelica is the flower of inspiration, and represents my Estate. A white, closed flower is beauty, whereas the petal shape represents beginnings. So my estate, interpreted florally, is the beginning of a beautiful inspiration. Aloe is the flower of religion and grief. A white, open flower represents truth, and the petal shape represents virtue. My character believes Catholicism to be true, even in the face of the major shift in perspective he's had, but he does somewhat long for the days he had as a human where everything was simpler. So Aloe seemed appropriate. Florally, this represents my character's personality as a virtuous, religious person who seeks the truth.
According to the table, the Code of Heaven's design background is usually none at all; the Angels used flowers during creation, and so flowers are the sole focus. I thought briefly about bucking this, and putting in a stylized crucifix, but I figured subtlety was better.