Fact is, that to make server balanced, Only rogue-classes should have restriction to wear the heavy armors. But if you want to screw it up, you will reach it by not letting the classes to use the armors if they don't have mastery. First of all, means that tyrants can't you heavy armors. That means also the summoners can't use light armors. After that let's think about olympiad buffing style, mostly classes like tanks, and all others are buffing with DC sets. in this situation it comes to the fact that most of them won't have enough time to buff, and it will screw the original gameplay. So please, make restrictions only for rogues, but let all others use it. That's quite obvious.