Last issue of the first mini is out today, so if you haven't yet read that, you may or may not want to read this.
I've been asked, a few times, about the exact nature of Luther's (and the Librarian's, by extension) powers, so I'll take a second to explain it. I think you should be able to get this from the comic, but I don't go in for the 'splainin much so I'll do it here.
For the right people, what The Hercules Method does is allow complete knowledge and conscious control over your body. At the most basic level, you get greater strength, speed and stamina, and perfect coordination. At the more advanced levels, you get the ability to make your body knit itself back together, which you see in six.
This same knowledge also gives you a couple of less obvious abilities. Because you are so in tune with your own body, you begin to be able to see other's people's body's the same way. What you're seeing with Luther's meatvision is a visual representation of that.
That same thing also allows Luther and the Librarian to tear people apart, because they know exactly where the weak points are. That they are superhumanly strong is helpful there, too.
Related to that is the ability to read body language, presented here as the millity billion ghost images Luther sees. It's not quite seeing the future so much as it is being really observant and having a terrific reaction time. The reason he can't really do that to the Librarian is because the Hercules Method allows the Librarian to control his body to cloak it from Luther.
Less obviously, it also allows you to hone your senses to greater than human levels. You see a wee bit of it in issue six.
None of this makes them invincible, as the Librarian found out. Destroy the brain or the heart or the spine, and they die.