HylianFox posted...
The NES game is the same way. Some enemies can't be hurt at all if you're not at a high enough level or are using the wrong sword.
I read that the GBC version did away with enemies being invulnerable to the wrong sword and instead makes them take less damage from it, though I can't say I extensively tested it out. I never ran into an enemy that was invulnerable to whatever sword I happened to be using at that moment, at least. Can't say much about the level thing, either, as I'm already conditioned to grind in old RPGs (thanks again, Phantasy Star) and hit the cap soon after reaching the pyramid (found out those mummies gave 1,000 EXP and got my last level ASAP).