Sacred
Sacred units are the "Warriors of the Faith" of the game's title, elite troops devoted to the Awakening God and particularly loyal to your nation's cause. Dominions 5 adds far more options to the game's sacreds than previous versions.
The most notable feature of sacred units is that they can be blessed by priests or the presence of a pretender during a battle in their own dominion. This causes the units to gain +1 morale, as well as all the effects of the pretender's bless that were chosen at the beginning of the game, plus additional effects gained from certain claimed thrones.
This means you can choose a particular suite of abilities that your sacred units will carry with them, and choosing a nation's bless is often a game-defining choice. Will you pick a few expensive, powerful unique abilities that require your pretender to be on the map, such as Regeneration or Awe? Or will you take a rainbow of minor blesses that combine to make your sacred troops efficient and durable combatants? Or will you eschew a powerful bless entirely for better scales?
Almost all nations have access to unique sacred troops that can only be recruited from their capital. Examples are EA Ermor's Equite of the Sacred Shroud, MA Agartha's Shard Guard, and LA Gath's Gibborim. They are often the single most powerful recruitable troops available to any nation; however, their numbers are limited. Each fort can recruit a number of sacreds per turn equal to your dominion strength; this means that nations with capital-only sacred troops are generally hard limited to about a half-dozen per turn.
Many commanders recruitable in any fort are sacred, such as Vanheim's Vanjarls.
A few nations have sacred troops that can be made from any fort, like Mictlan's Jaguar Warriors and MA Marignon's Knight of the Chalice. This is often a nation-defining feature.
A very few nations do not have sacred troops, such as MA Ulm and EA Mekone. A handful have sacred troops, but they are mostly a novelty and rarely used, such as MA Pythium's Battle Vestals and LA Bogarus' Khlysts.
Sacreds also have a halved upkeep cost compared to a non-sacred unit of the same gold cost.
A prophet is always blessed, even on the strategic map. Pretenders and disciples are always blessed in friendly dominion. Additionally, the Shroud of the Battle Saint allows any commander to become permanently blessed.
When 
blessed, the sacred icon changes to a form with lit candles.