Sekiro has been confirmed to have skill-trees, with skills being unlocked by doing certain side objectives and items and then bought using experience points. I wonder if this was a late addition to appease the casual flock. Skills have three trees (how original), Shinobi Arts, Samurai Arts and Prosthetic Arms.
Along with passive buffs and improvements to your basic moveset, you can also unlock special moves called combat arts, activated by pressing both front shoulder buttons and which must be equipped separately. These moves are meant to be periodic rewards that let you invest in a particular playstyle “just to give you something to make you feel like you’re roleplaying in a certain way,” says Kitao.
Personally I'm still on the flip-side. On the one hand more options are nice, on the other I had hoped it would be a pure action-title without all this fluff.