Shadow's Edge by Brent Weeks

It has been long enough that I don't exactly remember the breaks between the three books in the trilogy. But along the way, the story also becomes the story of Logan Gyre, the best friend of Kylar Stern - the reinvented Azoth, not quite master wetboy.

It seems that Kylar lacks the magical gift that allows wetboys to refer to their targets as "deaders" because they never fail, a gift which allows them to seem to become nearly invisible. Still, as the protege of the best of the best, Kylar is pretty good at the job.

He has moved up in the world, but his past never completely leaves him. His connections with the gangs of street rats still serve him - and he can never forget the child, Doll Girl, who was tortured to punish him.

In the meantime, there has been a coup, and in the moment of being married unwillingly to the corrupt king's daughter, Kylar's friend, Logan, is captured, his bride murdered, and he is thrown into the pit - from which there is no return.

Also, somewhere along the way, Kylar is forced to kill his master, Durzo Blint and thus inherits the secret of his power.