Belial was much, much easier after the patch. His damage in p2 decreased quite a bit. And in p3 I can sit still in the explosions and live now. Our problem was enrage timer, not dieing during normal part of the fight. Hit the enrage timer the first time, and specced for more damage to beat him the 2nd time. I even went dual wield on my barb it hurt so little.
Are you buffing yourself for more survivability at all? 500+ on resistences before or after using your shout? Should be 700-800ish AFTER the shout. Armor should be at least 8k. Rather than regear, change your passives etc to give yourself the survivability you need. I constantly change my skills depending on whether I need more survivability or damage. I can either have 6k armor or 10k armor depending on how I setup my skills. I barely hit 42k DPS when i have full frenzy and pop Wrath, so 42k base is massive for a barb. I can still run through stuff like butter with my DPS. Why insist on playing as a glass cannon when you have to stand next to shit that can hit you? Equip a shield, your game plays EXACTLY the same whether you have 2h/dual/1h-sh. Once your other stats are sufficient, go for more DPS when you need it with another weapon.