As stated above, Dark Vigor is supposed to give a 3% bonus to max health when a shadow ability it set, but summon shade doesnt do this even though its from that skill tree.
It even shows up as a 0% bonus when its the only shadow ability slotted, and testing it with weapon swaps it does indeed take away the bonus I get from having concealed weapon on my other bar.
Summon shade for me is at level 3, but I honestly doubt that'd make a difference. I know its not a big bug, but yeah, its there.
Thanks for reading.