In the Grandmaster Modifiers list it says “Maximum Effective Level 1815” however I tested Arbalest at 1828 and 1821 and got around a 3000 damage per shot difference, roughly 2% difference. In the YouTube link you’ll notice I did not apply the catalyst to the lower level weapon so I did and retested with the same exact result. The light level system is very confusing. I know there are changes coming but as it stands I have no idea at all what is intended or what will change. All I know is that for now pinnacles matter and so does your artifact; seemingly at least up to 1830. The Nightfall Grandmaster node in the director suggest a recommended power level of 1840, which would require artifact level 30. Get your grind on, folks. I’ll update when I’ve earned enough xp to push past 1830. Update: this effect only happens with weapons lower than 1810. Lower level armor has no effect on damage output so long as your light level is at or over 1815. I have not tested but it’s been reported 1810 armor is necessary for capped damage reduction, similar to 1810 weapons for damage. So for grand master you need only 5 artifact levels and full 1810 gear for the cap.