While FromSoftware games are often lauded for their difficulty, often there are certain builds players can use in order to make the game a lot easier for themselves. For the longest time, the Rivers of Blood katana in Elden Ring was completely broken in PvP and PvE.
Now, players have found the equivalent overpowered weapon in Armored Core VI: Fires of Rubicon. The Zimmerman shotguns, when paired up, are extremely effective in the mech action game. Good damage, strong stagger, great range, and more make the Zimmermans a must-have if you're struggling to deal with a certain boss or mission.
You also get the Zimmermans pretty early on, so if you are looking for an easier time, why not give them a go? They're not the only weapons dominating the meta right now, as miniguns, needle launchers, and Songbird rocket launchers are also pretty strong. Armored Core is all about bringing whatever build suits you to battle, so it's good there's not just one option that feels strong.