Bomb and Arrows completely destroy the armored phase of the Darknuts in Twilight Princess. Just aim the arrow at their feet. Guess the issue is the chainmail phase.
...I did not know this. Welp.
Ah well. It probably wouldn't have been as exciting if I knew this. Not that I always use the easiest methods for killing enemies. Honestly, sometimes, I handicap myself by purposely not using strong items, just to add more of a challenge factor, since newer Zelda games aren't very difficult in the enemy department. When I was playing through Wind Waker HD, I tried using the hammer instead of the sword for most fights. It actually made me have to think about when I'd take a swing, because it leaves you open for attack due to the delay, as opposed to the sword where you can mindlessly swing to win. It definitely made it more of a challenge, especially in Hero Mode, but it was fun.

