Truthseeker Quill

To bind ink to truth
Take a unicorn feather
Offered in friendship
The freer, the better
With freshly-burnt ash
From night-color'd flower
Fill bright feather's shaft
To lend the truth power
A fine silver nib
To write the truth with
Fit snugly to feather
By great Master smith

The pieces alone
Are but nib and a feather
Until woven, a spell
To join all together

Scribes differ as to whether the Truthseeker quill is named for its properties and common use, or after the owner of the very first such quill created. Whichever the case, it is a much-treasured tool which few private individuals will ever come to own - most are held by guilds or courts of law, where access to them is meticulously controlled.

Origin

Before Haven Sanctuary became what it is today, and simply was known as Freehaven, it was ruled by a generally benevolent Free-Lord, who claimed no land beyond his city and the fields his subjects worked, and who refused to swear an oath of allegiance to any King or court. Freehaven was relatively successful as an independent lordship for a time, though there were time when one bordering nation or another attempted force the Free-Lord's hand by closing trade routes with the city, hoping that becoming a vassal of would seem a small price to pay for the reopening of trade. When such measures failed, a newly-crowned ruler decided to put a much bloodier end to the thorn in their side that was the continued independence of Freehaven.
The city's population was decimated as it was overrun by the foreign army, shields painted black and wearing no ruler's colors, and any person encountered in the central keep slain in an effort to eradicate the Free-Lord's line. By pure dumb luck the Free-Lord's cousin Lady Emyla Freehaven was late returning from a ride due to her horse taking lame, and managed to escape the carnage unscathed. When she returned, she found her city in shock and her family murdered, and resolved to not only help her people heal from the trauma, but also to make the people responsible for all these deaths answer for the callous slaughter. When finding the perpetrators proved easier said than done, and all chances of resolving the situation through official diplomacy seemingly exhausted, she entrusted the running of the lordship to the heads of the Guilds, extracting from them a promise that they would not neglect the plights of any subject who had no Guild to speak for them, and rode out to seek the truth through other channels.
At one point during her search, she crossed paths with an avicorn, and they exchanged tales of how they came to be in that place, at that time. The avicorn, a mage, was touched by Lady Emyla's plight and impressed by the lengths she was going to in order to unveil the truth of her family's fate as well as that of so many of her cousin's subjects. From his own wing he plucked the largest, brightest feather, and touching it with his horn he cast a spell on it. He then gifted the enchanted feather to his temporary travel companion, bidding her to make of it a quill, which would permit no falsehoods to be written down. Though it was not yet named as such, this was the first Truthseeker quill.
Word of the Lady's quest, once it spread, earned her the moniker Truthseeker, and the measures she put into place for running the city in her absence were eventually made permanent, remaining much the same to this day.

Forgeries

Many attempts have been made both to replicate the function of the Truthseeker quill with less precious materials, to forge quills that appear to be legitimate in order to defraud, and to create an ink that will counteract its magic and thus allow lies to be written. Neither of the former two have seen any success, while the third has seen limited success with the inclusion of finely-ground Whitestone in an ink - such ink can indeed negate the Truthseeker quill's magic. It is, however, easy to detect, as the fragments of Whitestone make the ink glisten even when dry, as well as altering the flow of the ink and making it rough and scratchy to write with. The main accomplishment in creating this Whitestone-infused ink, thus, lies in the creation of a visually catching ink that sees some decorative use among a subset of those who engage in regular written correspondence for pleasure.

Mechanics & Inner Workings

While the traditional, sanctioned creation of the quill requires a total of four ingredients, the only ones strictly necessary for its construction are the unicorn feather and the enchantment. The burned black flower petals are strictly superstitious symbolism for the destruction of lies and deception, that serves no actual function for the finished product, while the silver nib was added as a practical measure to prevent the very valuable instrument from wearing down from regular use. That the nib needs to be crafted by a silversmith of the Master rank in a Jeweler's Guild is another piece of superstition that makes no difference as long as it's a well-crafted, functional nib made of silver.
The spell used to enchant a Truthseeker quill is fairly advanced, and quite delicate until the casting is complete. Any interruption or mistake is liable to make the cast fail, with the worst case scenario being a misfire that renders the feather unusable. Once cast, however, it draws upon the inherent purifying powers of unicorns, and along with it their inability to speak that which they know to be untrue, to channel those qualities into the core function of a writing instrument: to commit words to paper, parchment, or other similar surfaces. This results in a quill pen that will not put down ink if one attempts to use it to write down a lie.
If a quill is fitted with a silver nib, as is common, it will not suffer from any significant wear and tear through simple use, while quills manufactured from feather and enchantment alone will suffer the same wear and need to periodically trim the feather shaft for a fresh writing tip as an ordinary writing quill, albeit at greater intervals than with mundane quills. The magical properties of the Truthseeker quill are, however, slowly depleted with every falsehood that a user attempts to note down. Once fully depleted the quill will "wilt," the barbs of the feather curling and darkening as if singed, and the silver nib, if it has one, tarnishing.
Used nibs can be polished up and re-used without ill effect, but often are instead melted down for stock out of superstitious fear that they hold enough residual deception in them to prematurely deplete another Truthseeker quill crafted with them.

Manufacturing process

The first, and most difficult, step to creating a Truthseeker quill is finding a unicorn willing to part with one of its feathers of its own free will and without coercion. Molted feathers will not work; the feather must be plucked from a unicorn's wing or body with its full consent. This is doubly difficult as unicorns do not have feathers. Luckily, for the purposes of creating a Truthseeker quill, hybrid creatures of unicorn heritage, such as avicorns and unihippogryphs, seem to do just fine. Nevertheless, procuring one of these feathers is a difficult process at the best of times. For all that the original owners of the feathers typically value truth highly, they're not often keen to lose more than one or two feathers between molts, particularly if they don't otherwise deal much with literate civilization.
Petals from whatever black flower might be local to the maker - or whatever they might be able to get from a trader, if none grow locally - are usually dried, then heated to their flash point in a small metal scoop or pan. This can also be done by introducing an ignition source directly, though that is considered an inferior method. The ideal burn is slow and even, reducing the petals to ash at a uniform rate. In practice, this is not often accomplished except by magical means, though craftsmen who specialize in artifact-making may take pride in working towards perfecting their particular technique. Once the petals have been reduced to ash, the ashes, preferably still warm, are meticulously inserted inside the feather shaft, taking care to do minimal damage to the shaft in the process. Junior crafters are often made to practice countless times with feathers from large domestic fowl and ashes from the fireplace before being entrusted with their first real project.
The silver nib, usually also including a grip section to protect the shaft of the feather from the grip of the user, is typically commissioned from the local Jewelers' Guild, which will be supplied with very precise measurements as regards the desired length of the grip and the diameter of the hole where the feather will be seated. The ideal result would be a snug friction-fit that only needs additional securing as a backup. The methods of securing the feather within its seating vary, but most popular is the use of needle-thin pins run through the shaft of the feather and secured in some sort of decorative metalwork.
Once the quill is assembled, it is time for it to be enchanted. The spellwork doesn't require additional reagents, but does require a high level of precision and the utmost focus for the full duration of the cast; while the casting is in progress even very minor disruptions can result in needing to start over. In rare cases, the spell doesn't so much fizzle as dramatically misfire at that point, and may even destroy the near-finished artifact in the process. Once the spell is completed, however, it is a magically durable item that presents a significant challenge should someone wish to drain it of magic or otherwise destroy its enchantment.

Significance

Truthseeker quills have allowed courts to ensure that witness statements are to the best of the witness's knowledge not outright falsehoods, thus aiding in the prosecution of serious crime. They are generally not used for lesser offenses, due to the expense and difficulty of obtaining new ones. In some places they have also become favored tools for signing important contracts; the parties do not only sign their names, but also write a phrase to the effect that they fully intend to uphold their end of the contract. If the quill won't write the phrase for either party, that individual pays a fine to the owner of the quill for the wear on the artifact, and likely stands to lose any opportunity to do local business as word gets out about their presumed intent to violate the contract.
One complication that does arise from the use of Truthseeker quills in a legal context is the misconception among the general populace, and often also the legal system, that what is written using them must be correct and objectively true. This is not the case; the quill is not sentient, much less all-knowing, and only can detect lies that the writer is deliberately telling, not them simply being wrong about something.

Item type

Tool

Rarity

Relatively rare, but not irreplaceable

Dimensions

Typically around one ell in length

Raw materials & Components

A unicorn feather
The ash from burning a black flower
A silver quill nib