When it comes to the fighting in Zelda games, only really the classics are hard and require fast reflexes.
The puzzles can be different for everyone but eventually if you play enough Zelda games you'll be able to beat most dungeons without help.
I'm not sure if you can freeze Morpha, but you can freeze Bongo Bongo and activate a new animation using the ice arrows. Maybe you misheard? They are both bosses meant to be fought before you obtain the ice arrows.