A concept, Epic level divine classes "Share" piety with those around them, if they share the same god or alignment +1step & Same aspects.
Epic level clerics : Standard, Evangelist, Cloistered - Share 0.1 - 0.2 piety per tick to those around them
Warpriests, Seekers & Defilers share extra on enemy kill in a party.
Druids : Share 0.1-0.2 to those around them whilst in a natural area.
Favored Soul : Shares 0.1-0.2 to those around them
Shamans : ? Possibly, Hard to say as RP can be different
Paladins/Rangers, perhaps at 26 they get +Piety uptick, not sure about sharing.
This would add both flavour and benefit, as they would maintain peoples piety from dropping with their presence (When epic) And give a focus on actually representing a deity