The book reads life an introduction to these and a few more characters and their backstories, with whispers of legends and history in conversations. They move forward, some of them together in an untested association, other alone, to stay afloat in a high stakes game of war and politics in which they are somewhere between player and pawn.
The Blade Itself doesn't take the grim-dark sub-genre of fantasy fiction to another level. It is stripped of old ideas of heroism and romance but it doesn't introduce enough fresh events, grit and politics. Glokta's backstory sounds intriguing, as does Logen's and Bayaz', but we aren't given more than a few details. There is a magic system with time dilation and some reality bending physics but other than establishing Bayaz' credentials and lending a sense of legends past the book doesn't have much use for it yet.
The book excels in introducing the characters and leading the reader into the next books in the trilogy. There are several threads not just of the characters but also of world building that are left unexplained.