Dark champions of Necropolis.

I understand. In that case, it would be better to revert the sword's color to green. Firstly, it looks better that way, and green is essentially the primary color of the undead, while purple is just an alternative. As for the dragon, it's up to you. Perhaps it would be better to color the dragon itself in purple and use that color to tint some elements, just as you did with black. For example, the eyes, mouth, or some elements of the wings.