basically the event that created relics is like a second coming of Christ, humanity banded together to cast away some malignant evil so the big houses were recompensed with relics fitting for their role & narratives
the relics are literal artifacts, they can be any objects (i was also playing with the idea of organic or formless objects (like a rainbow))
there can exist multiple copies of the same relic
relics can become "incarnate" as "human beings" (i wouldn't exactly call them human, its more like weapons in soul eater, they are still a separate life form)
each relic has a set number of incarnations and a set frequency of incarnation
it depends on many many conditions lol
so the stuff about "1st cycle" means its the first time that specific relic object has become human
while they're in relic forms they can be used to the house's will
when they're incarnate they have their own will
once the last cycle is complete, the house that owns the relic dies out
its like a prolonged death note
there are ways to "freeze" incarnated relics by placing them into gestational receptacles (wombs) which are themselves also relics (a funny side effect of this is that a womb can become incarnated while being used...)
i think that sets down the basis of it so let me just copy my characters/relics descriptions now

> The Knight (2nd cycle: Plumed Bloodshed); a castle-dwelling knight, manifestation of the relic “Volkspoesie”. A free incarnation, he holds a place of note in his estate, and seeks to document all reported apparitions in search of unknown relics, tediously advances national self-interest by gnawing at Prejnystrian & [Silesian] border, historical claims of continuity. Owns an orchard. Incessant correspondence. Plans to accelerate the cycle of death and rebirth of relics in order to put an end to the stagnant deadlock of his era. Has no illusions about the fate of his own bloodline, nor about the impossibility of accompanying humanity into its dying breaths, as per his fantasies.

Other:
1. “Faustina’s Confession” allows the neutralization of any other relic’s attribute. Of the four known specimens, three have reached the natural end of their lifespans along with their respective bloodlines. The number of cycles for this relic varies from 1 to 4, and its incarnation rate is abnormally frequent. The families who had acquired “Faustina’s Confession” were deeply affiliated with the Church and known for their piety. Due to its high incarnation rate and short natural lifetime, using this powerful attribute is fairly difficult, as it requires permanently placing the incarnation into gestation from birth, slaughtering it to return the object to its artifactual form, and using its attribute. The cruelty of this process explains why it has never been strategically utilized. The last remaining relic is an incarnation, “1st cycle: Mercy for the Boy”, currently in gestation under military supervision. Has the particular trait of requiring constant incarnation and overriding the limit on simultaneously active incarnations; the birth of a manifestation of FC will instantaneously end the incarnation cycle of a different relic.

2.  “Black Veil” allows a malleability of decay and prosperity, with the drawback of a universal arbitrary tax (its demand can be as negligible as a penny per person, or as crippling as five eyes per estate). It can be used perpetually without additional cost (a rarity) if certain demands are met. In its incarnated form, “Black Veil” manifests as hypertrophy; cancer outbreaks, two-headed calves, infested gardens, quintuplets & consequent deaths in childbirth, incessant storms.

3. “Volkspoesie” allows the manipulation of others’ speech and offers a considerable improvement of the user’s persuasion skills. Scales off of the user’s literacy and pride, which is why it has never been sought after by thieves. Though not its primary purpose, it has historically been used by the possessing estate to insert themselves into local folklore, even laying claim to certain fabricated exploits on a scale exceeding their own kingdom. Low incarnation rate. Has been known to herald territorial conflict but otherwise seemingly inoffensive when incarnated. Requires a proximity of 30ft for direct speech alteration, but for more subtle obfuscations its efficacy depends on national borders & sentimental predisposition.

4. “La Balayeuse” allows the casting of a prolonged night, and, under certain circumstances, a prolonged winter. Typically incarnated amongst illegitimate children, disgraced members of the bloodline; “all is filth on the lady’s tail—all must be swept away”. Possessed by the Russian crown. Has the exact same effect when incarnated, only involuntary. Geographical limitations vary on the conditions at the time of use, and on the user’s identity. The last incarnation, “8th cycle: O Adelaide” brought forth a winter so harsh that the Spanish mines had been said to have frozen over, at home and abroad.

5. “Heart-to-Heart”; a game of Russian roulette begins upon activation, with the user and a chosen opponent competing in their resolve, righteousness, or purity… the exact nature of the quality that allows a victory is not yet determined, and some claim the result of the trial to be completely arbitrary. The loser’s heart bursts, and the winner historically flays him to be displayed. Private courtrooms, mass executions possible as long as the value on both sides is comparable: many can be “one opponent” in spirit. The energy collected in these explosions is accumulated, the blood of a player runs across fields and ballrooms, enriching the steaks and grasses alike; new joys, new colors, new ideas, new music, it is the most productive estate relative to its population size. Blood oasis in mountainous and desert land, decentralization.

6. “Va-et-vient” allows modification of physical spaces deemed within the will of the user. The spaces inhabited or visited by the user become an extension of his person and a representation of his will, allowing him to modify them from a distance. The closer an object is to the user’s center of existence (the space most familiar to him, the one he has the best knowledge of), the more freedom in overriding and transcribing the reality. If another individual has stronger will and knowledge of a space that has been modified, he may notice the discrepancy, in which case the illusion shatters and the space returns to its previous state. Additionally, in this scenario, the user of “Va-et-Vient” is banned from the space, physically unable to breach it. As such, a guest who tries to modify a perceptive host’s environment is promptly cast out—parasites must be discrete.

7. “Down Cast Die” draws out one’s internal perturbations to make of them a weapon corresponding to its user. The greater one’s unrest, the greater the conjured object. However, every dice cast will see one downcast die: those plagued with fear, misery, and anxiety risk a fatal roll with every turn, which is why, while it is possible to summon nearly any object that one may desire, the relic is typically not wasted on trivialities (the few collectors to have gotten hold of it gambled themselves to an early grave). The term “weapon” is most appropriate: the conjuring attribute has only been activated in times of war and civil unrest, but by nature the artefact is not an armory: it can summon cheap ale as it can live elephants, and a skilled wielder may hoard much paraphernalia. Scales off luck and neurosis.

There’s a balanced number of incarnations in the world at all times
There are relics devoted to information gathering, clairvoyance, defense, counter-attacks, etc
Basically any specialized use you can think of
And naturally different factions may use them differently

as a writing exercise i wrote the equivalent of a "hunters' exam" arc in universe:

Event Objective: Recruit 5 to 7 members to retrieve stagnant relic “Ecumenical Telegram” from the general area of Thuringia/West Saxony.

The test will be administered in three parts by three members of the National Kulturkammer, themselves selected by the Knight’s personal advisory board for their experience in assignments and expeditions of similar nature. Administrative connections and handsome rewards are granted to the selected contestants & families (among other things, unrestricted access to a class of relics owned by notorious collector […], member of Volkspoesie’s advisory board). There are 400 initial applicants.

Phase 1, administered by the Hierophant [Finnish Cannibal], can best be described as an ordinary written exam. It consists of 3 sections: history, literature, scripture. The purpose of this exam is mostly unrelated to the recruitment objective, and rather serves to assess the effectiveness of the Department of Popular Enlightenment’s activities on the most restless class of participants. The effects of Volkspoesie facilitate historical revisionism, but this relic proves essentially useless for dispassionate scholars and clergymen, since it scales off of nationalism and is mostly propagated through pagan folklore. The exams are graded and returned, but the selection does not depend on one’s failing or passing the test in the literal sense—each applicant’s psyche is reconstructed from their answers (which include critical analysis), and the administrators look for strong predictors of traits such as stealth, perceptiveness, and a slight nationalistic inclination. Anomalies are taken note of, and typically pass to the next stage for further analysis.

Of the 400 initial applicants, 270 were seemingly illiterate, either leaving their papers blank, misusing their pens (and thus being unable to fill out the required documents), or writing illegible gibberish. They were disqualified, as illiteracy is a significant predictor for suggestibility, and illiterate mercenaries perform poorly in relic retrieval. While Volkspoesie keeps them on task, they tend to stagnate when first encountering the influence of a foreign relic. Of the remaining 130 applicants, 40 were members of the clergy. Of the 37 that passed to the next phase, 2 failed to identify Friedrich I as the founder of national program “Weg zur Frömmigkeit (Path to Piety)”, instead attributing the initiative to an [Austrian] national. The 3 that did not pass to the next phase were withheld for their marked resentment of the gestational practice for the preservation of stagnant relics. Of the remaining 90 applicants, 35 self-identified as “mercenaries” or “warriors”, 27 as “scholars”, 7 as various mythological creatures, 6 as “nomads”, 6 as a title falling under “noble”, 5 as “N/A”, and 4 as “aides”/“pages”. As expected, the greatest variety of discrepancies between the national historical account and the participants’ answers was found among scholars, of which 4 refused to acknowledge well-documented [genocide] entirely, while 13 gave reluctant answers regarding its cultural effects. Self-identified mercenaries had the most impressive familiarity with local folklore, while pages the least, seemingly unable to identify the archetypes represented in the provided excerpts, instead recalling foreign literature and scripture when asked.

Phase 2, administered by the Crane, takes place on an eastern lakeshore, where a mass of criminals has been moved from a selection of fortresses and ranger stations. They have all, in one way or another, violated the law, though the contestants have no information about the nature of their crime, or their backgrounds. The criminals outnumber the contestants 5:1. Among the present individuals, 14 are thieves who have been blessed by an unregistered relic, giving their teeth the peculiar medicinal property of complete immunity to most viral and bacterial infections, as well as a high nutritional value. The contestants must choose which criminals to kill. A kill rate exceeding 75% is an automatic mass failure. Restraints are placed on the criminals’ speech so that they cannot convey information directly divulging either the nature of their crime, or their history of crime. Certain criminals will attempt to kill the contestants, others will cooperate. Killing other contestants is permitted, and will not affect the aforementioned “kill rate”.