Your right, it is the hardest weapon to get if you didn't push him off the edge like a lot of people are doing to beat him. I know someone that hasn't made it past the confluxes on hard mode but has a Mytoclast for each of his characters cause he knows how to get to Atheon without killing anyone.. Thats why they nerfed it and yes the patch should be separate for PvP like how you keep ammo when you swap special weapons you keep half your ammo in PvE only.