Devices and Desires by K J Parker

I enjoyed this more than The Company, possibly because it is drawn on a somewhat larger scale. There's certain common elements - extremely competent characters driven to extremes by various flaws and it is possibly set in the same world.

It tells the story of an engineer sentenced to death for making improvements on a mechanical design, one of the worst crimes in the city-state where he lives (they are the renowned machine-makers of the world). This sets into motion a cascade of events that causes war and destruction, and looks set to cause even more in the following couple of volumes in the trilogy.

I also approve of Parker writing fantasy without magic, monsters and all that stuff. Just people in a different, apparently totally normal world doing their thing. Admittedly, his main characters are almost supernaturally good at everything they do, but only to an unlikely extent rather than an unbelievable one.