I’ve tried various combinations and generally arrived at the same conclusion. Regardless of whether I was attempting a fire/phys or a pure fire version, getting sufficient skill bonuses on EoR and Soulfire on two-handers is a bitch and even if you do get your EoR and Soulfire maxed out to get that juicy flat damage, you’re kneecapped by low attack speed (even perfectly rolled Gavel struggles to crest 150 % with max Vindictive Flame and best possible Embergrip Handguards, which I think are BiS). Then, after all that, you’re still losing damage compared to dual-wielded Alladrah’s Spellblades because you have no room to convert the lightning from Soulfire, you don’t have any added flat fire damage to the skill on two-handers, and if you’re trying for a pure fire version you don’t even get 100 % phys to fire conversion. Meanwhile, Alladrah’s Spellblades boost both EoR and Soulfire and provide full lightning-to-fire and phys-to-fire conversion in one item. So, ironically, the class combination that IMO would make the most sense to just play a straight Fire or Phys/Fire EoR with a big weapon is better off finding a way to dual-wield what is primarily a Shaman/Oathkeeper weapon than something like Infernal Brimstone or Blazerush or something.
I’m not saying two-handed EoR Shieldbreaker is unplayable or anything, but in the end what should theoretically be the most straighforward way to build an EoR character (EoR deals phys, fire and lightning, Demo supports all three, has the necessary elemental resist reductions and auras to quietly do work behind the scenes while you’re spinning) ends up grasping at straws to find a big meaty two-handed weapon that actually makes any sense for the build. Switching from any of the two-handers I mentioned to Alladrah’s Spellblades on this build boosted my damage output by over 50 %.