This whole story was shockingly close to my first run there last week (where I played the role of the terrible WHM)- so much so that I had to read it twice and found myself sighing with relief at the words "today" and "also has a 60 PLD", both of which rule me out as your specific reference there. I apologize on that WHM's behalf either way though.
In my case, I don't recall exactly what I expected the orb to look like when the mechanic was being explained (and to be fair, the 'explanation' was 1 long line of text 5 seconds before pulling), but I do recall the reality being so different from what I imagined that it took too long to react to it, so... death by orb. And the team valiantly fought atop my corpse to a heroic victory, making my instantaneous early death that much more humiliating.
I find it more embarrassing that so many people responded and not one seemed to consider the possibility of confusion over Holy being a self-centered AOE and not enemy-targeted. Even the person who gave you the answer seemed to do so accidentally. Given that it's the only offensive spell WHMs have which is designed that way to that point, it's not an unreasonable mistake IMO (and probably a really common one)- it took me a few attempts to figure it out as well.
