In the novels, the Witch King of Angmar is described as having the ability to break weapons or kill opponents even when they contact his body. This was so severe that it was worse than a blow from his mace. Moreover, he can be death threats with just his voice. This explains why Aragorn used his torch instead of his sword while facing off against Nazgul on Weathertop.

https://specialstl.com/article/witch-king-of-angmar