It is really hard to defeat darknuts in this game. You seem to never be fast enough to see when and where(high or low) You get stabbed. What are your tactics for defeating darknuts in this game? Do they have any pattern?
If you watch closely,you can see that the Darknut's sword is visible behind its head when its about to attack high and its sword appears behind its back just before it attacks low. It might be hard to watch for it when you are trying not to die in the real game. I suggest watching part 2 of the Zelda Dungeon video walkthrough. There is a Darknut fight at 4:35. You can see what I'm talking about. Once you get used to looking for the cue, it is easier to dodge the darknut attacks. Mases uses a strategy of jumping into the Darknuts that also works really well, but it takes some time to master.
Also, another helpful tip, when there is only one Darknut between you and the dungeon item, I use thee down thrust to hop over them and get straight to the item. Of course you have to get the down thrust first.
For the Red and Orange ones, since I find the jump technique makes me take too much damage, I like to rush them. I stab them high then low then high etc. Although, you do need to be on the look-out for their attacks. I also find if you run in, stab it, retreat, repeat, also works sometimes against them.
For the blue ones that shoot beams from their swords, hit them back away and block their beams then go in for another hit and back away to block the next wave of beams.