[Snake]

lmfao

75% damage reduction on Sword, Axe and Spear if you put your back against a wall
Around 40 Critical Evade
Bonus 10% reduction to all physical damage for using heavy armor, and goes up to 20%+ if using offensive skills
A torso that further increases that to 50%
+6% bonus DEF
Not even counting your actual DEF investment.

Black Knight's theme, since pre-GR, was to be a wall against physical damage. So I think it is fine as it is. Adding methods of combating magic would make it way too overkill. Especially when the class that are /supposed/ to be anti-magic only perform poorly against it because people are always greedy for big dick damage and don't build right or get the right equipment.

If you only invest in STR/DEF and not VIT/RES, or like Spoops said, use a shield, which is a further 10%/30%/70% reduction on top of whatever elemental resistances said shield grants to you (I know some give +30% in one element), that's more a you problem for trying to use Two-Handed and go for damage and expect to not get 100-0'd against your nat counter.

But 'MAYBE' just 'MAYBE', they could get an incurable 1 round silence at a rank 5, on a sword autohit that they should get in the future. Since that's the only weapon type they lack for an offensive skill.