I've painted a lot of bright stormcast and now I am working on a few tweaked, darker stormcast for AoS 28.
There will be 3 and each will lead a separate warband containing the dregs of order.
Whilst mystery is often cliché, it is also dark. Knowledge is the light. As such, to fit AoS 28 these 3 stormcast will be drenched in mystery.
Their heraldry is known - the chalice, Bronze with sea blue armour with orange trim. Outwardly bright, inwardly dark.
They share nothing with their warbands.
They seldom meet with other stormcast but if they were to meet they would be nearly as stoic as with the lesser folk of the realms.
If forced to, or if it serves their end goal, they will let it be known that their Warrior Chamber is "Equites Calice" and nothing more.
For once this information is shared, no more questions are forthcoming. Their fellow stormcast understand. Or at least they think they do.