You choose the weapon.
You choose the Expertise.
You choose the Technique.
You read several percentages.
Then, ideally, the percentages happen.
Whirlwind players are increasingly convinced that some of them do not.
A long-running bug report from the Barbarian community says several Weapon Expertise bonuses are behaving inconsistently with Whirlwind, particularly when Dust Devils and certain build combinations are involved. The issue has been tested by players for weeks and is still being discussed as of August 14.
Blizzard has not officially confirmed the problem, so this remains a community-tested bug report rather than an established developer finding.
But if the testing is correct, some Whirlwind Barbarians may have been optimizing around bonuses that were not actually doing what they thought.
Dust Devils Appear to Ignore Weapon Expertise
The biggest complaint concerns Dust Devils created through Whirlwind.
According to the original report, Barbarian players testing different Weapon Expertise options found that none of the tested Techniques appeared to modify the damage of the Dust Devils generated by Whirlwind.
That feels particularly strange because Dust Devils have become deeply integrated into modern Whirlwind builds.
Blizzard has repeatedly updated the interaction over the last several seasons, including changing Dust Devil damage and giving Whirlwind-generated Dust Devils additional offensive utility.
From a player's perspective, if the Dust Devils are part of what the Whirlwind build is producing, it is natural to expect the Barbarian's weapon bonuses to matter somewhere in that equation.
According to the testers, they currently do not.
Polearm and 2H Axe May Have an Even Stranger Problem
The second issue is more specific.
Players report that Polearm and Two-Handed Axe Expertise initially affect Whirlwind itself, but under certain setups the bonuses disappear roughly half a second into the channel.
The reported combination involves Aspect of Anger Management and Whirlwind's Tornado modifier.
When testers removed the relevant gear and modifier, they say the Expertise bonuses began working normally for the full Whirlwind channel again.
That is the sort of interaction that makes Diablo build testing delightful.
Remove one legendary power.
Change one skill option.
Discover that your axe has apparently remembered how to be an axe again.
2H Sword Appears to Work Better, But Not Completely
The community has also tested Two-Handed Sword Expertise.
According to the same bug-report thread, it appears to work on Whirlwind's direct damage more consistently than Polearm or Two-Handed Axe.
But even here, players report that the bonus still does not carry over to the Dust Devils.
So "working" comes with an asterisk large enough to require its own weapon slot.
This May Have Affected Build Guides
That is where the issue becomes more important than an obscure tooltip disagreement.
Players in the thread note that Polearm Expertise had continued appearing in Whirlwind recommendations while the problem was being investigated.
The original tester later explained that the community itself had largely taken the interaction for granted until theorycrafters began checking the actual numbers and noticed damage was missing.
That does not mean every Whirlwind guide has been fundamentally wrong.
It does mean the expected value of certain Weapon Expertise choices may be different if the community testing proves accurate.
And in an endgame where people happily rearrange half a Paragon board for a few percent more damage, that matters.
We Don’t Know How Long It Has Been Happening
There is also uncertainty around when the behavior began.
One player believed Polearm Expertise worked normally during Season 13.
Another tester says the community is no longer confident about that and considers it possible the problem has existed for much longer without being noticed.
That is plausible simply because Diablo 4's damage systems are enormously complicated.
When a build contains multiple Expertise bonuses, aspects, skill modifiers, Paragon effects and secondary damage sources, a missing multiplier does not necessarily announce itself with flashing red text.
Sometimes the monster just dies slightly less enthusiastically.
For Now, Treat the Testing as Community Evidence
At the time of writing, Blizzard has not responded publicly to the bug report or confirmed that Weapon Expertise is malfunctioning with Whirlwind.
That distinction is important.
The testing described by players is detailed and has been repeated across several weeks, but it remains player testing.
If you are running Whirlwind, it may nevertheless be worth checking your current Weapon Technique rather than assuming every listed bonus is affecting every part of the build.
Especially if your damage seems lower than the spreadsheet promised.
Because somewhere in Sanctuary, there is apparently a Barbarian staring at a Polearm and asking the most dangerous question in modern Diablo:
Is this percentage actually doing anything?
Sources
Diablo IV Forums: Barbarian Expertise Not Functioning Properly for Whirlwind
Blizzard Entertainment: Diablo IV Patch Notes
