Rejuvenated by the victory I return to face Friede and promptly get face stomped again and again. I do improve though, up to the point where I slay her! But this is Dark Souls, that doesn't really mean I won. See by doing that Ariandel goes ape shit and revives her.
Oh, so the boss fight only starts -now-?
Now I have to fight both a nunja, and a crazed giant bird wielding a cup full of lava! Even with Sir Gael's assistance, this does not end well for me and defeat resets the fight -fully- as per usual.
I opt to head back (bonfire warp works just fine) and chat with Corynx who gives me clues where to find more Estus shards (more healing). I manage to find two more which is still not a full set but it proves to be enough to slay both Friede and Ariandel! Huzzah!
This leads to phase THREE, where our favourite nunja revives again - this time with dual scythes (I guess she killed Scythegirl too) and insane dark magic moves. Yep. I die again. A lot. And this resets the fight -fully-. :P