I'm have no real preferences, but these are some anime that i enjoyed that'll likely work for him:
- Souten Kouro (essentially the Dynasty Warriors anime... with more blood... mmmm Lu Bu shish kebab)
- Ghost in the Shell (basically a shot in the dark, also depends on which one)
- Deadman Wonderland (manga is better, but it's still pretty solid)
- Mirai Nikki (there is a love interest but she is a yandere and rather disturbing at times)
- Akagi (it isn't gory, but the plot is rather well done, and he may like it if he enjoyed Death Note)
- Dangan Ronpa
I'm gonna keep looking through my anime list, but these and Nosebleed's suggestions should be enough for a while