I've always liked the Needle weapons in the fiction and the tabletop game, but I don't grasp how they work in Dark Heresy. I believe the corebook says that if they hit, they do N impact damage (I forget what the roll actually is), then the target has to roll against toughness or something and take damage from the poison. In either case, the target takes a number of wound points. If those wound points consume their wound threshold/points (dropping them below 0), the hit is a critical and you'd roll on on the Impact table based on the hit location. This doesn't make any sense to me, since what actually happened is that while the needles themselves could have done some shredding damage, it's really the poison that kills you, so "leg blown off" for example doesn't make any sense - you're dying (or died) of a neurotoxin.

As my understanding is obviously wrong, can anyone correct me? Thanks.

actually it does rending damage, so the arm getting ripped off can be justified as the needle just punches through the arm or body and cleaves off a limb, then the weight of rending fire would make the targets limbs become a lot less well attached to his body.

Thanks, that's what I thought, but for some reason I had it in my head that the core DH book had them as impact weapons for some reason.

Ignore the Critical Result flavor text if it doesn't make sense. Obviously you can't cut off somebody's arm with a small knife, so just say that the guy died of shock or something. Same thing with poison. Note: Blood Loss is not literal Blood Loss, it is slowly dying.

It could be justified to do impact damage.

Just imagine someone being poisoned convulsing and spasming and hurting himself in the process.

And, as was already said, just modify the flavor texts to fit the situation.

I remember playing Warhammer FRPG some years ago when my dwarven char used to kill giants with the "the hit rips of the target's head" critical result. And we always found it hard to imagine a Dwarf jumping high enough to hit a giant in the head with his mace.

Or some other RPG, where a hit with a twohanded sword could inflict two independend criticals in one hit, resulting, for example in cutting off the right ear and damaging the left hamstring with one strike.

Losing blood isn't slowly dying?