Flaming arrows, spears, and knives have no problem finding their way to the back of a mouth. The profanity is delightful. And the general atmosphere is grim. The movie just isn't terribly inspired.
There are, by my count, six standard types of violence in film these days: Tarantino, comic book, Scorsese, martial arts, horror and stupid. That's right: stupid. For an example, look no further than Centurion.
The film has a resigned bitterness, hard to shake off, that feels right for the experience of tough guys, from whatever period of history, who find themselves at the tattered edge of what they take to be civilization.
Most of the characters are so characterless that you can't tell who they are when they get impaled or beheaded, and you can't remember who they used to be after they're dispatched. Not that it matters.