I notice in the final panels where White Chain says, basically, to accept the wheel turning, there are petals on the tree.

Symbolically, that would support my suspicion that Angels can be grouped in terms of tree parts or stages (Root Knight, Thorn Knight, Petal Knight). Note that flowers, petals, beget fruit. And White Chain has been trending towards change, womanhood, she was holding a baby in a panel in a maternal way…

She might be the first…uh…“Fruit Knight”. But probably named something else. Plum Knight? Given plums, not apples, are the holy fruit in this universe? Would go well with purple, too. Or maybe Seed Knight.