The issue is the game is rarely (certain traps...) unfairly hard. You figure out your build (strength/stamina for me) and learn enemy patterns and focus on health and ki. It even allows for grinding and two player mode if it is too hard for some.
Love Nioh and seriously think this could unseat Bloodborne (which I freaking love) as my game of this console generation. If you have any interest I strongly suggest buying Nioh.