Warrior Hundred Blades
Bumping because this bug does still exist and I can reproduce it pretty reliably using the method stated above. The animation for the final hit will play, but there is no corresponding damage indicator.
Did you check the log? Not the white numbers poping up on the mob
Okay, so I figured out how to actually reproduce the problem and why it happens.
It has to do with the duration of the quickness boon granted by activating Berserk. During a typical Berserk → Arcing Slice → HB combo, the quickness boon will fall off right before the final strike occurs and apparently cancels it altogether. If you skip on using Arcing Slice and go right into Berserk → HB, you’ll get the full 9 strikes because the quickness boon will last the entire animation. Likewise, you can circumvent the problem by giving yourself boon duration.
This still does not feel like intended behavior. Even if the quickness falls off, the 9th strike should still happen.
Okay, so I figured out how to actually reproduce the problem and why it happens.
It has to do with the duration of the quickness boon granted by activating Berserk. During a typical Berserk -> Arcing Slice -> HB combo, the quickness boon will fall off right before the final strike occurs and apparently cancels it altogether. If you skip on using Arcing Slice and go right into Berserk -> HB, you’ll get the full 9 strikes because the quickness boon will last the entire animation. Likewise, you can circumvent the problem by giving yourself boon duration.This still does not feel like intended behavior. Even if the quickness falls off, the 9th strike should still happen.
Nice detective work (apparently not the only issue with quickness).
Besides mentioning it here, I recommend you copy/paste the text above to the in-game /bug reporting tool right after using 100B under quickness — that will help by giving ANet direct access to the same data you collected.