Perhaps I didn't word it very well. It's partly what's said in the book and it's partly what my vivid imagination makes of what's said. The latter is more or less photographic in it's clarity. I can accept things like character A beheads character B with one swipe of his sword, because all my imagination makes of that is literally the head coming off. If it's not in the text then I generally don't imagine things like blood and gore. But some things just sound so horrific that they freak me out. A good example of this would be a book I was reading a few years ago. Having got into the Dragon Lance series several years ago, I had also extended into the Forgotten Realms spin off series, not knowing then that the FR authors were given more of a free hand in the content, so at times there would be more explicit violence. I got on with them at first and really loved some of them, such as Azure Bonds.
Then I bought the Druidholme Trilogy and began reading the first volume - Prophet of Moonshae. I wasn't too far into the book when I came across a scene that couldn't be more tranquil - a grassy hill with a shepherd tending his sheep. Tranquil until a dragon swooped down and, as the author put it, disembowelled the shepherd with a casual flick of it's foot. And that did it for me. I could vividly see the wound, the bowels hanging out, the blood and gore, and I could imagine the shepherd laying there, not yet dead, in indescribable agony.
So I stopped reading the book, gave it away along with the other two in the trilogy and, after hearing that some modern Dragon Lance titles had become the same, just stuck to the early titles in the series, along with other authors who I knew didn't write such scenes into their stories, such as Brandon Sanderson.
I wish I wasn't like this but I can't do much about it. I'm highly sensitised to such things and avoid them as much as possible. But I also love fantasy fiction.