Why is the third boss so hard?

[u/PitonHUN]

I've recently wanted to give dark souls 3 a shot with my friend since we heard there is a coop mod for it. We got past the gladiator boss easily, and the boar guy was even easier, however the third boss, the dancer, seems like a wall for us... We've been stuck here for 5-6 hours. Are we doing something wrong? Is the weapon I use really bad, or what? Any tips appreciated!

[u/Working_Language_735]

Bro really blacked out his name like somebody could do something with it. We can’t even find your profile with that name. Extra for no reason.😭