maxed all traits on my Hero before RED maplestory2 patch. Once, I believed it works on Gollux, but only him. I will have to test again. I exactly do half damage on all end game bosses even with 10% elemental resistance from Insight, so I think this stat is bugged.
And also, is the 10% elemental resistance ignore 10% of the 50% damage reduction so we deal 45% less damage than normal boss OR we deal 40% less than normal boss? o.O
This would really benefit most classes with max insight if the stat works correctly. Certain classes can already ignore 100% elemental resistance, like certain cygnus knight classes and mage explorers!! Also, paladin post RED and pre-nerf had 100% too.
I want to know if the this part of trait is really bugged or just works on certain bosses. I can say it doesnt work on Magnus, Root Abyss and certain more.
If some people can confirm if it works well or not, i would like to know. If its bugged, then I will make a thread in Bug section.
EDIT: I just read on strategywiki and they say the max level insight gives total 5% ignore monster's elemental resistance. I was sure it was 10%, unless i confused with max ambition.
As AKradian mentionned, its ignore elemental resistance. With this trait, you are suppose to ignore boss physical resistance (considering as an elemental resistance) unless i am wrong. On end game bosses, except for explorer mages since they have 100% decrease element resistance, it should help other classes to deal a few more damage.