The city guard is composed of both volunteer and mercenary hired by Baron Sevrin. He neglects his responsibilities to the watch, but has appointed accomplished leaders that keep the watch well in line. He's placed his son, Lord Sevrin in charge of the Blue Watch, the elite fighting arm of the watch. The Blues are composed of well trained fighters, volunteer clerics, and specially trained wizard apprentices.
The general watch is made up of "lifers" as well as a constant flow of volunteers, where the volunteers are made up of the men in families that could not pay their taxes. Five years in the watch clears their debt and buys them a year's reprieve of taxes after they leave.
The Blue Watch is the elite guard. Their normal function is to keep the nobles and wizards safe. Patrolling the Wizard's and Noble's Section of Rokmil keeps them busy for the most part. They will also police special events, escort visiting emissaries, investigate brutal crimes, and such.