A lance aligned with the psychic plane, capable of dispelling Light.
I regret to disclose that the Cryptarchy's following report on the so-called "Synaptic Spear" is woefully ill-prepared, even coming as it does from the few fledgling Cryptarchs who are not busy studying Savathûn's throne world. I myself am overseeing the construction of the Psisorium, where a Psionically gifted individual could theoretically scan through the networked memories of preserved minds, but I digress…
Based as it is on the Light-suppressing technology that Dominus Ghaul used to restrain the Traveler during the Red War, the Synaptic Spear is capable of interrupting or dispelling a single instance of Light if, and only if, it is wielded by a Lightbearer. However, this repellant effect is too weak to be of any use in the physical plane—the spear is only capable of disrupting Light in an environment charged with Psionic energies.
Even then, it cannot be used against a subject unless they are also a Lightbearer (perish the thought!) who believes themselves in such a perilous situation that they manifest an aspect of their Light in the Psionic environment. That aspect could then, it is theorized, be slain by the spear, leaving the subject Lightless in the physical plane.
In short, Commander, any use of the Synaptic Spear relies on a truly improbable chain of hypotheticals. With such an inconceivably narrow usage, it is difficult to imagine how this spear will be of any use to us in the battles ahead.