In the Mahud special rules on p14 of the Harad sourcebook it says 'Poisened Blowpipe. The poisened blowpipe can be fired in the Shooting phase if the bearer did not move in the preceding Move phase.'
But in the Hasharin profile it says 'A Hashirin carries... a blowpipe (treat it as a bow...)'
So the Hashirin can move up to 3" and fire his blowpipe (as per normal bow rules). The Mahud cannot.
The Hasharin do however benefit from the Bane of Kings which is better than the Poisened Arrow Rule! Each time a Hashirin strikes a model with a ranged or close combat attack, but fails to wound he must re-roll the dice. That is much better than just re-rolling on 1s
