[PvK]

The passive ability is called "Halt Heretic"; that's what I had in mind. It's on the unit.

The weapon ability I know of is called "Bane of Heresy", and it is an aoe fatigue effect.

At least, according to the MA Ulm Lord Guardian, that's what they are called.

"Halt Sacred" sounds like a misnamed "Halt Heretic" (the awe effect on the unit), unless it's something else I've not heard of.