Is this a feature or Glitch for Damage stats?

I noticed that when i have Damage elixir my damage increases awesomely and if i want to increase it more with pets giving damage boost, it doesn't,unless i increase my primary stats.
Also when using pet with damage boost and using shadow viel at same time doesn't increase damage. Just hoping that this is not a feature and a glitch

The highest percent buff is the only one calculated.

Eg: if I have Slag (+12% damage) equipped and cast a charged VB I have +25% damage only. If I have ribbit equipped (no passive damage percent) and cast a charged VB I still have +25%. Only the highest percent buff is considered. This also applies to percent based armor buffs like this EOF the bulwark proc, veils, and the AAs of littlebear and glacian.