According to the rules, psykers take a -4 penalty to all power rolls while sustaining another psychic power. So wouldn't this make the weaken veil power (provides +2 to power rolls) useless to the psyker that is sustaining it?

Weaken Veil isn't really a power that a psyker uses for themselves, it's more of a power you use against other psykers.

But in this case sustaining weaken veil would be at a -2 instead of a -4.

Personally, my psyker has stayed far, far away from weaken veil. I roll way to many 9's to want this power.

DastardlyIceHole said:

I wondered about the same just recently, but realized it is a great psychic power to be used by villains like the Pilgrims of Hayte that are mainly interested in overall destruction. This way you can keep any annoying Psykers in the party (or maybe in an powerful opposing Psyker from a players viewpoint) in check. I plan to use this as the first manifested power by a False Prohet my players are about to confront in the near future and I am really looking forward how the party's Psyker will react and how one Psychic Phaenomena after the other will manifest...