I literally just got done finishing my first playthrough of Dark Souls and I'll say that world traversal and exploration are definitely harder in Souls but the bosses in Sekiro are much, much harder. Artorias was nuts but a lot of the difficulty of the bosses in Souls really came to me not having the right equipment for the job (weak armor/shield or weak DPS) where it was an issue of skill and memorization in Sekiro. Definitely feel the bosses are better designed and more skill based in Sekiro, which should be the case, they're designing things better as the years go on.
Well that’s kinda what I’m saying.
Honestly the most difficult boss for me in Sekiro was Lady Butterfly, but she taught me the flow of combat for the entire game. After her I (obviously still died a lot) felt like i figured the game out and and it was pretty easy for me.
Bosses fell into two categories. Aggressive attacks and parrying in order to break posture, or patient dodges and blocks, to take one or two swipes during an opening.
I like the idea of the souls games forcing you to learn some new skills and/or push your character to acquire new weapons/powers.
That’s what I felt was missing in Sekiro.