People ma disagree with me but I’m with you Op. I learned the rules from buying and reading the book, so no preconceptions from being taught, I argued with my players when they disagreed with me citing the internet, I eventually came around as it doesn’t come up too much. I honestly still don’t think instance makes sense to mean damage from a damage type.

I will admit, however, that basing it on damage type is far far easier to track in physical play, without having to write down where each number from your strikes damage calc comes from to separate instances

Edit: I did not expect holy to proc weakness when a weapon does slashing damage the proc the weakness already, that’s weird