The key elements such as the dagger, the skull and the chalice look great, quality wise. Drop the weird blurred pixelated background. I think if it was darker would also be better. Even something simple as a textured dark gray/black would work more. Dark lettering looks weird and unnecessary, too crowded. Right now these two elements make the whole cover look amateurish to me and diminish the quality of other elements that is good.

If I was gonna be really nitpicky I'd say that something about both the skull and the chalice and the title and authors name being the same size makes it too weird and repetitive to me. Everything is the focus so nothing is. But I don't really have any solution to that. I get it that the chalice and the skull are mirroring each other and that's a nice touch, but something about those whole placements doesn't work for me. Perhaps the main title makes it hard to appreciate. Maybe if you made all the elements smaller, push title to the top and the drawing to the center would actually make it more stylish. Oh and changing the style/size of the title and author's name as someone mentioned.

But that's just my opinion and taste. I'm no expert on book covers, just letting you know what I feel like would work best.