Shiv's Rage doesn't work on all items

[VastoL0rde]

Shiv's amp doesn't work on Headshot Booster, Headhunter, Backstabber and Scourge.
The damage values stay the same as normal.
While Items like Mystical Shot, Cold Front, Arctic Blast, Alchemical Fire, Tesla Bullets all enjoy the 25% Rage damage amplification.

 

[Samosvalovich]

The fact it works on decay and doesnt work on scourge makes literally no sense btw