I was cruising around in the lake (doesn't matter which one), decked out in jewelry that made me invincible with resist normal weapons 100% among the enchantments (I made myself some god items). I was playing on maximum difficulty, when an ordinary slaughterfish came up. I wasn't worried that I'd be damaged in the least, so I let it hit me. He one-hit-killed me! I tried letting a mud crab hit me with the same situation, to see if the normal weapons enchantment fell through, but it hit me and did nothing, not a scratch. I tried an ordinary slaughterfish, again. One-hit-kill! Is the slaughterfish's attack not effected by weapon resistance, what I call "piercing", like a silver weapon or enchanted weapon?