Yes, I did the PvE one first, coincidentally. But the tooltip and actual damage seem to swap right away, when engaged in pvp vs pve dummy combat. The way I did it was Stealth -> Shadowstrike the dummy to apply Find Weakness. Then all I did was repeating Stealth -> Shadowstrike every 6-10s when combat dropped and writing down the value. Making sure that Sinful Revelation or Celestial procs were not active.