The way things are now, the Sabotage function has been completely emasculated. I've attacked the same village 5 times with 3 and four spies each time, and NOT ONE ATTACK resulted in a loss of a building point. It's useless as a Hall Of Orders.
My suggestion is this. If you want a THIEVES Guild, make them Thieves. Let them target the Warehouse of an enemy city and steal resources. Let them target the Statue of an enemy city and steal one of the Paladin's Weapons. Maybe it would be possible for the spies to just be more effective, having a better chance of gathering info without being killed, or let the Hall of Orders create Super Spies who, if successful, can go to an enemy city and stay there (like a support), but will instead hinder the defenses of the city (lower their luck, reduce the effectiveness of the walls, etc...).
If you want Assassins, then make them Assassins. Have them able to kill Officers (Master of Loot, Grandmaster, Medic, Tactician, Deceiver, etc..., maybe even the Paladin or a Noble.)
Nobody seems to like Sabotage the way it is... not even the poor saps who chose it. This feature really needs to change.