Reworking Hidden Attack:
Instead Hidden Attack should be controllable. All other skills are active, they don't have a chance to happen. Presumably, the formula has a set percentage chance to happen over a period of time. The fact that it triggers against forts and oasis wastes these hidden attacks when we could actually make use of them.
Now obviously if Hidden Attack was always active this would be very powerful and every player would max it out. Instead Hidden Attack should be usable whenever we want to use it during a set period of time dependent on the level. Every point into Hidden Attack decreases the 'cooldown' by an hour all the down to 1 hour at 10th level. This way once per hour period you can choose when your attack will be hidden. While this would potentially decrease the number of hidden attacks attainable in an hour, the ability to control when your attack is hidden is much more valuable.
Also, there's a really bad bug with hidden command. Sometimes as the attacker I can't command a hidden attack till round 2, sometimes 3. That alone was reason enough to reset my skills because it's happened to me a lot.