general in Terraria

Update to the nights edge situation, found out I need 20 of each the mech boss souls in order to get true nights edge. thanks terraria 1.4
Ok, so I got the nights edge, by going to a different world to use a demon altar there, and I have a broken hero sword, b u t, I tried using it in my main world and it wouldn't work, I'm at the mythril anvil and nothing happens am I doing something wrong?
Ok does anybody remember the fetid backknacks from terraria? how before 1.4 they were insanely fast and strong but only did 64 dmg? Well they have the psycho knife now, basically fetid backnacks but does 110 dmg and has the original speed, thanks game :>
im thinking of doing calamity mod for my YT, which class should i pick, im thinking of summoner, ranger, or rogue, and maybe melee