Negates any wound on a 4+. In hand-to-hand combat any wound saved by the amulet is rebounded against the foe, no saving throw allowed, not even for magic armour.

The Black Amulet is not armour. It will work against any magic weapon which normally ignores armour. It will even work against a weapon which ignores magic armour. The Black Amulet's save is not modified for the strength of attack, but gives a straight 4+ save. Any wounds saved by the Black Amulet are rebounded against the attacker, but note that it cannot rebound the magical effects of weapons. It simply rebounds each wound struck. In the case of magic weapons that score multiple wounds (eg 'each unsaved wound = D3 wounds') take the Black Amulet's save before multiplying the wounds. In this case wounds will only be multiplied if the Black Amulet fails to save.