Pope Leo mottoe
"In Illo uno unum" : "In the One, we are One"
Burning heart arrow : The symbolism of a "burning heart" often represents deep emotional intensity, passion, and fervent love. In various traditions, it can signify internal conflict, yearning for truth, or a profound connection to one's feelings and purpose.
https://www.wisdomlib.org/concept/burning-heart
Most notably, the fleur-de-lis is depicted on the traditional coat of arms of France that was used from the High Middle Ages until the French Revolution in 1792
https://en.wikipedia.org/wiki/Fleur-de-lis