Hello,
I already submitted a bug report on this, but here's what is going on currently:
Putting points into Mighty (increased physical damage) did not increase damage at all on skills like Surprise Attack or Lethal Arrow according to tooltip.
Lethal Arrow might have been explained by it dealing Poison damage instead, so I tested by putting points into Thaumaturge; same problem, tooltip indicated it was dealing the same damage as before I put those points in.
This has a potentially huge impact on combat balance, if it turns out to be more than a UI error (which I didn't have time to test).
Is the team aware of this,
@ZOS_JessicaFolsom ,
@ZOS_GinaBruno ?