That can be fixed by changing the factors that affect difficulty. Instead of giving the enemies less health or making your attacks stronger, give the player more health or weaken the attacks of enemies on easier modes. This would result in each combat experience being roughly equal in length and intensity, but allowing a more novice player to make mistakes and soak attacks that would be fatal in higher difficulties. You would still be able to experience an enemy’s special mechanics.
This scales well in the other direction as well - say an enemy has a powerful attack that you need to dodge. On easy, you can maybe tank 3 of them from full health, medium is 2, hard is 1, and nightmare is a one-shot kill.
Another scaling option is the speed of enemies either movement speed or the time it takes for them to land hits, attack animation timing, etc.