Ravenpen

A ravenpen is a writing utensil used for the creation of spellbooks. As the name implies, they are fashioned from the remains of a raven, most usually a single one of its feathers fashioned into a quill. However, this is not the only possible configuration. A raven's claw can be used to create a scratching form of pen, scraping into clay blocks. (Spellbooks do not have to be "books" in the modern sense.) Even those who prefer parchment or paper may wish to look beyond mere feathers, as more powerful spells sometimes require ink also contain raven components. Traditionally, this means ink that is 5% by volume raven's blood.
As a more economical alternative, crow's feathers (and claws, and blood) may be used. As you'd expect, this is called a crowpen and tends to be seen as the bargain bin option. This simply is a misconception -- a ravenpen is more appropriate for spellbooks intended for offensive magic, while a crowpen works better at support magic. It is thought this is connected to the intelligence of these birds; ravens are said to be more solitary, while crows are social birds who survive together.
In Daoirse's timeline, peacock feathers are often sold by charlatans to young mages who may believe that a flashier quill results in stronger spells. In truth, these quills tend to channel the writer's magic poorly and are only appropriate for spells involving arrangement of cutlery.
As magic did not exist in the "main" timeline until relatively recently, the only known user of spellbooks in this timeline is Daoirse. Having spent many hours making spellbooks for her former allies, she has the stamina to mass-produce them, but has trouble remembering the finer details of her own enchantments. As such, it is a trial-and-error process, resulting in her making spellbooks with only a handful of uses. Any books with more seven spells tend to be unstable, even if crafted with the freshest of ravenpens.

Mechanics & Inner Workings

The pen is not so much magical as it is an excellent channel for magic. For this reason, they are useless in the hands of someone who doesn't know what they are doing.

Current Holder

Daoirse

Rarity

As it is not itself enchanted until in a mage's hands, they can be collected by anybody capable of catching ravens. Thus, their rarity is tied to the rarity of corvids in the area.

Raw materials & Components

Daoirse typically uses roadkill for her spell components, as it is cheap, relatively plentiful, and arguably slightly more ethical than hunting. So long as she shares a body with lapsed-vegan Sleepy Saoirse, it may be her only option.
Strictly speaking, a regular ballpoint pen with a raven's feather duct-taped onto it is a ravenpen, and can be used in truly dire circumstances, such as if someone has access to roadkill, Bic pens, and notebooks inside an Office Supply Max but does not know the art of fashioning a quill. But this is not recommend, as modern pens tend to explode when the requisite amount of magic is channel through them, spraying ink and small shards of cheap plastic into the caster's hand and clothes.

Tools

Traditionally, they are cut with a silver blades, but Daoirse has found that X-Acto Knives work just as well.