I'm looking for an official answer to this question. From everything I've seen so far, technically, you would lower your Fatigue Threshold when you get Fatigued. It just seems so much like an oversight. The idea that you pass out "when your Fatigue is equal to your Tb plus your WPb and die when it's double that" is so simple and easy, but if you look at the rulebook like a lawyer it seems that in reality, that's a very misleading answer to the question "When do I pass out and when do I die?" since your normal, unfatigued Fatigue Threshold will never actually be used for anything.

From everything I've seen so far, technically, you would lower your Fatigue Threshold when you get Fatigued. It just seems so much like an oversight.

Where does it say that? You gain levels of Fatigue and you compare it with the Fatigue threshold to determine if your character passes out (Fatigue level exceeding the threshold) or dies (in case the Fatigue level exceeds double the threshold amount). Where does it say that the threshold lowers when your character becomes more fatigued?

Maybe you meant the representation of Fatigue and how much a character can take is wrongly represented in your opinion. Though I don't get why you'd think that the Fatigue Threshold "will never actually be used for anything", it clearly IS used.

Maybe I'm missing your point.

From the FAQ ( https://images-cdn.fantasyflightgames.com/filer_public/72/55/7255f060-deb3-46af-879e-bebc9c699abb/dark_heresy_2nd_ed_faq_v12.pdf )

Question: When a characteristic is fatigued (page 233), does this also halve the associated characteristic bonus?

Answer: Yes, the bonus is also reduced for any purpose it is used. This means fatigued Agility reduces Movement rates, fatigued Strength reduces inflicted damage from most melee weapons, fatigued Toughness reduced damage mitigation, and so on.

Since the bonus of Toughness and Willpower will be reduced by fatigue " for any purpose it is used" I think it is a valid point that the actual Fatigue Threshold is also reduced as SpaceRobot suspects.

But I'm not sure if this is intended. Maybe it would be worth having a clarification by Tim?

Ohhh Fatigued Characteristics. Personally I'd say the Fatigue Threshold is an exception, but an official answer would still be nice.

I think it makes more sense to use a character's unmodified values for fatigue threshold for 2 reasons. 1) Lowering the threshold every time a character gains fatigue turns a punishing mechanic into a lethal mechanic, and 2) recalculating your fatigue threshold every time you take fatigue adds needless complexity onto an already complex game.

Still, the wording is unclear and someone should probably email FFG about this.