Mystic vicious sword?

The group all stared at Seth with wide eyes depicting confusion and fear at the same time. Before their very own eyes, they watched as the woman they all presumed to be injured who turned out not to be completely normal fell to the ground dead and her body reddish because it appeared her skin was peeled off.

Seth had surprised the group, pulling a mysteriously long sword with a rough blade out that released blue foggy smoke from it, he had attacked the woman while she was still alive but this only ended up with the current situation where it appeared as though the woman's skin had touched him and the rest of the events that happened wasn't seen clearly by the gang. All they knew then was that Seth wasn't acting normal in any sort of way.