Poisonburst Arrow and Exploit Weakness

Poisonburst Arrow recommends Exploit Weakness as a support but after testing :

The projectile consumes the Armour Break but the poison doesn't seem to be affected by the 50% more damage. I assume it's because the poison burst says it doesn't hit.

Either the interaction is meant to work and there is a bug, or the support shouldn't be recommended.

I used gas arrow + corrosion + demolisher for the armour break.