like curses. only good. Basicly what would happen if a creature that worshipped a certain god did something spectacular in a deities sphere that diety might reward them with something appropriate. It shouldn't be under player control and would be semirandom.
An example of a weak, more common type of blessing could be an animal deity giving blessings to a dwarf which makes it so normal animals won't attack that dwarf or any dwarf near him. The reasons for this should be semirandom. but an example of could be that the dwarf is the first worshipper of that deity to tame a certain animal.
A rarer and more powerful blessing could be a water deity giving immunity to drowning. others with varing rarities could be:
immunity to heat and cold
other immunities
undead don't attack you (death)
superstats/skills of varying types and degrees
voluntary shapeshifting
agelessness
the ability to make artifacts at will.
having a child with a deity [probably not really be a blessing vut would happen for similar reasons]
true ressurection after a heroic sacrifice.
one of the rarest could be multiple ressurections under certain differing circumstances. possibly like your body has to be functional, so no missing a head. another one may be a ressurection every time a character dies after an obvious heroic sacrifice. Like stopping a goblin army attacking and massacaring multiple inncent towns and cities. This type of blessing should ussually come with a lot of strings and mountains of fine print. so even a careful player could still die permenantly. and by rare I mean a adventure mode player may get this sort of blessing once every five real time years of playing nearly every day with pious characters trying to get blessings.
etc.
A possible idea could be that even if something doesn't a worship a deity they may give out blessing if the act is great enough. Maybe each time the game considers a blessing it may make it less likely the more prior blessing a creature has gotten. one blessing may happen on average in one in a hundred of whatever population. two blessing may happen in one in a thousand. three may be one in ten thousand. [on average since it should be semirandom]. maybe once or twice in a very long world gen [or very,
very, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very veryvery, very very, very very very very very very very very very very very very very very very very very very very very very very very very
very rarely an adventurer or fortress dwarf] something might be given enough blessings to be more or less immortal. three or four types of multiple ressurections with fine print that cancels out with the fine print of the other types , agelessness, immunities to syndromes, heat, cold, etc. maybe with super strength, inteligence and other stats. insane rng luch, etc. This doesn't mean that can't be killed. you'd just have to chop their bodies up into tiny little pieces, burn each piece separately and bury the ashes on opposite sides of the world.
for any one who says this is overpowered. one consider how rare I said this would be. two consider how the more common ones would more or less useless outtside of very specific situations. most blessings would just be a minor character trait. And to get the rare ones would probably result in sucicide most of the time. three, if you still have a problem I wouldn't be opposed to adding drawbacks. like a healing blessing removed if the blessed commits a violent act and similar things.