Laws on Magic

Alchemy

Performing most Alchemy outside of the empire's borders is illegal without express permission.

Blood magic

Blood is very important to Eideli culture (after all, they worship the sovereign of Blood). While most know that alchemy uses blood, common knowledge is vague past that. Only state-sponsored alchemists are legally allowed to work with blood, part of the government's hold on the practice. It's nowhere near as restrictive or exclusive as the Contractor organization from Whirlpool, but still requires some background checks and loyalty tests. Of course, there's also a competency test, including literacy, basic theory, and practical application.
Those born to alchemists are exempt from this, with the expectation that they register themselves before adulthood. As a result, first-generation alchemists are generally seen as inferior due to the practice being restricted until a much later age. However, as plant-based alchemy isn't forbidden, several innovations have come from first-gens forced to take unconventional approaches. Entrenched alchemists are sometimes criticized for simply throwing more blood at a problem instead of improving their algorithms and approaches, something one with a plant-research background couldn't afford to do.

Spindle creation

Spindle Creation
The human sacrifice invovled in spindle creation is something of an open secret amongst the more educated upper class. It's considered treason punishable by execution to divulge this information to outsiders (not the ritual, just the fact that they're crafted from humans) despite many considering it obvious. It's simply one of those uncomfortable truths which most conveniently ignore. The link to spindles and blood magic isn't super obvious either, since they don't have any visible flesh or blood. The creation process mummifies the insides, so examining a broken spindle limb wouldn't provide immediate answers either.
Note that the link between human sacrifice and spindle creation is actually a rather well-hidden secret to the wider world. This isn't as stupid as it seems from an outside perspective. Cotd, for example, have familiars which act very similarly to spindles in terms of feeding mechanism and general shadowy aesthetic. Those are more well-known to be bound echoes with no human component. Echoes/puppeteers being a well-known phenomenon amongst most binding or otherwise spiritually aligned cultures, most come to the conclusion that there is some sort of spirit well within the Eideli empire from which they manufacture spindles. This isn't even technically false- most echoes are drawn from the edges of Naomhsgire, a swirling vortex of darkness where Eid is said to make her house. It's just that spindles actually also contain a (very diminished) human soul. In fact, there were intially worries of the stonewyrm blessing being able to reveal this secret. Luckily, the standard spindle creation method expends most soul energy in order to flub the final construct (an even further extreme than Cotd flubbing), leaving a much diminished soul easily masked by the puppeteer's Celestial energies being stretched around it. Hiding the secret of spindle creation is part of why knowledge of alchemy is so heavily guarded. Complex, non-theoretical alchemy tends to make use of blood and such- to practitioners, sacrifice of a whole body isn't much of a stretch. The common people, however, just believe that blood preservation exists as ammunition for xiphaem wielders. While true to an extent, it also sees use in alchemical purposes. The fact that most lower-level alchemy works with plants and inorganic substances helps to mask this further.

Xiphaem

Xiphaem technically falls under the same blood magic restrictions that advanced alchemy does, consequently requiring the same license.

Sharp Blood

The transport of sharp blood in an easily accessible container is restricted to military and government officials. Noble families technically count as the latter, and are consequently generally seen in posession of a sharp blood bottle when travelling. In order to fully legally do so, one must be in posession of an orichalcum coin if carrying the blood. Enforcement of this can be rather stringent, often used as a way to strongarm poorer houses or otherwise inconvenience them.
It also creates more of a pressure to obtain a coin, especially in seedier areas: a bottle of sharp blood is incredibly useful for self-defense, especially against multiple opponents.