I read John Ringo when I was younger (early 20's); it has a lot of what you are looking for.

I wouldn't call it high art, but the writing is fairly good.

I mean sounds like you want gore. if you wanted softcore porn piers anthony is the way to go but I can't think of something more brutal than gore. going to be interesting to read replies and see what else is out there.

It's not as much violent but Weaveworld by Clive Barker is in that dark fantasy vein, very good, very long.

Also dark, kinda cosmic, very good, is Imajica, also by Clive Barker. It's almost 900 pages tho so you've been warned.

Gritty and gory? Black leopard, Red Wolf

Check out James Enge. He wrote a series that I really enjoyed that sounds like just what you are looking for.

Absolutely "The Library at Mount Char" by Scott Hawkins

Saving this thread because I'm curious