Vect is known to super-murder all psykers he comes across and most other Kabals tend to follow suit, so being from a typical Kabal is unlikely. However, there is another alternative, which is to be either from Low Commorragh, or from a Kabal sponsored by the Baron.
If you check his page in the old Codex, Baron Sathonyx previously was known to bring a psyker, a Farseer of all things, back with him on one of his raids, and got tossed out of the Kabal of the Slashed Eye for it. Now, that may seem like an argument for why he'd be done with psykers, but he actually ended up becoming the Hellion Lord and controlling the Slashed Eye from behind the scenes from then on...what's more, he did so with psyker-related shenanigans, namely the bones of his Farseer which he casts in blood to see glimpses of the future.
I have a feeling that if anyone was harbouring, capturing, gathering, or even training psykers in Commorragh, it would the Baron, who could have possibly been saving them up as a special force to use against Vect in the long term, if not for the sudden appearance of the Ynnari screwing that plan up. I've personally wondered if the Baron would go Ynnari (though I doubt it), however, his secret psykers could have defected to them, or might even have started off by spying on the Ynnari for them after they made a fool of Vect.
Also, in regards to the theories by the others, I would agree that Power From Pain is most likely a unique psyker ability for the Drukhari, and that their psyker abilites have just been rearranged, as BBBacon suggested to be similar to a penguin's wings.