A typical psyk-out device
A psyk-out is a protective anti-psyker device used by the Imperium of Sidhae.
While top-tier Imperial operatives do receive training in recognizing and resisting a psychic attack, due to the extreme rarity of psykers actually capable of causing harm in the Sidh home universe, dedicated anti-psyker devices are exceedingly rare and exotic.
A psyk-out functions in a manner not unlike a Mecharussian/Frenkish neural circuit-breaker, causing a feedback of psionic energy in a psi-attuned brain. However, unlike a circuit-breaker, which is a passive measure intended for disabling or killing a hapless psionic attacker making a direct attack against the subject, a psyk-out is an active and much more potent implement also possible to use offensively. In a way, a psyk-out device is an anti-psionic exhibitor, causing massive psionic disruption in a large area of effect upon activation.
Psyk-outs are usually designed in the form of pendants or rosaries featuring some prominent Imperial symbol, making them inconspicuous and easy to conceal. The technology behind them is never explained in-universe, but is described as bordering on the arcane even by Sidh standards, indicating a very complicated manufacturing process and most probably a price tag to match.
A non-psychic individual will perceive the nearby activation of a psyk-out merely as a bout of intense migraine accompanied by a brief blurring and reddening of vision and unpleasant high-pitched tinnitus and possibly minor nosebleeds, the effects rarely being incapacitating and lasting no more than 10-15 minutes after exposure. For a psionic individual to happen within a psyk-out's area of effect, however, is a virtually-assured sentence of agonizing death, the psyk-out effects being likened to a detonation of an atomic bomb in one's head. Psi-sensitive individuals will invariably suffer immediate incapacitation by excruciating pain and massive cerebral hemorrhage. Those who survive the immediate aftermath are practically guaranteed some degree of lasting physical and mental disability. Furthermore, the effects increase proportionately to the individual's psionic potential, although exceptionally-powerful psykers (on the level of an archaelect) can shield themselves from a psyk-out strike.
Due to the rarity and sensitive character of such artifacts, psyk-outs are only issued to the most prominent Imperial servants, who are the likeliest to be targeted by enemy psykers. Possession of one can thus be considered as much a mark of status as an article of protection. One individual known to possess a psyk-out is Arcadius Drax, although even in his case it is not certain whether the device is in his permanent ownership, or merely issued for the duration of his diplomatic mission to A-1, the Mecharussian/Frenkish home universe.