Go "Versatile" instead [this is even better for an integral heavy stubber]: +3 damage on the first successful attacks [times how many hits?], good extras to hit, and… a decent anti-tank weapon with Opportunistic.

1d5-2 times twenty integrity instead of bouncing off? YES PLEASE

Well, unless you're tzeench-aligned with a slayer limb. Then you may as well just up the output.

a decent anti-tank weapon with Opportunistic.

1d5-2 times twenty integrity instead of bouncing off? YES PLEASE

I'm not quite sure whether that bonus of Opportunistic doesn't only apply to Zealous Fury hits that now deal d5-2 instead of 1 point of damage if they wouldn't inflict any otherwise.

Those seem to be seperate points and sentences. You'd do 1 on ZH regardless of toughness or armor if it triggered, not 0.

If it were to only affect Zealous Hatred, it would be generally a downgrade, losing your certain piddling 1 damage in exchange for a 40% chance of doing 0