The more I think about it the less doubt I have that it could've been done with Weapons of Light and snipers. We had a 33 in the party after all.
I've posted it before. The problem is nobody actually gave it a good effort. People gave up after a couple hours, which is disappointing. Level 34 content, which is the max level, should be tough content. There is already Level 32 and 28 PoE, why should 34 be a cakewalk too? It shouldn't be the hardest but it's OK if it takes more than a few hours to figure it out. It sure did for us on our first try (we actually gave up with a 33) and then came back the next night and solidified our strategy.
No Horns at all victory (sloppy):
https://www.youtube.com/watch?v=lS3gf9_ybi4
1 Horn but no spamming (clean victory):
https://www.youtube.com/watch?v=Dp_1mgAGI98
We did it once with 0 Gjallahorns and no Weapons of Light. The second time one guy used a Gjallahorn sparingly and that was mostly to clean out adds. Still no Weapons of Light. My sniper wasn't even fully leveled and I am awful at hitting crits. The encounter was not hard, it just required coordination and patience, which 90% of the player base does not have because they are used to spoon fed victories with Gjallahorn. The same thing happened with Skolas, the first strategy was to burn him with Horns because that is everyone's instinct when in fact the sniping/shotgun strategies are way better. Maybe it's poor game design, it's the same reason you had level 32 people running around during The Dark Below that still didn't know how to do the bridge section because they never did it legit. The skill level isn't there because people have never been forced to actually learn the game.
The reason it becomes a bullet sponge fight now is because the detainment shields won't be enough to kill you if you don't have the buff. They'll take you to low health but you could already get through them before. They've effectively made it so the mechanic can be ignored and you can just focus on picking away at the boss without other worries.