When you reform the Roman Empire as the Byzantine Empire you can no longer equip the Imperial Diadem. This seems like a bug or an oversight, but seeing as it has been this long, I'm wondering why both emperors can't wear it.
active = {
is_feudal = yes
has_landed_title = e_byzantium
}
active = {
is_feudal = yes
has_landed_title = e_byzantium
}