With such an immense number of weapons to choose from there are bound to be balancing problems - and they were - but they were never game breaking. You could live with with rapier/shild guys and killing the wee bastards was satysfying as hell.
The thing is, Castello is a map consisting in a large part of corridors which is easy to exploit by the fire bomb throwers. I think we all know of which part of the map I speak of, when I mention the fire-fueled 27fps hell hole.
To my mind, fire bombs on Castello should be banned. And I know it kinda defines the idea of using any weapon you want anywhere, but they literaly ruin the gameplay on this map (not to mention already shaky performance.)