My archer is packing 6 IF... That might be why, they could have built them to not explode from a feint breez aka arb bolts.
It goes down to build, always has always will. A guy with 8IF 8PS and 69 points of armour, is going to flip you upside down and fuck you in the face... not going to go down from one shot. Hell I couched a plate user with a great lance at full trot on a rouncey... he got back up.
TL:DR HERP YOUNG DERPINGTONS HERP LIKE YOU MEAN IT! DERP.