Learning
Learning is a secondary skill, that increases the amount of experience a hero gains from different events. The bonus may be 5%, 10% or 15% depending on the level of the skill. For example, if a hero without Learning secondary skill recieves 1000 experience points from a treasure chest, a hero with at basic level of Learining would gain 1050 points, at advanced level 1100 points and at expert level 1150 points.
Discussion
Learning has an excellent idea, but the execution fails completely.
If a hero would have an expert level of Learning from the beginning of the game, it would mean that when the hero has achieved 230'000 experience points, a hero without the skill would have achieved 200'000 points. This would mean that the first hero is on level 26 and the second on level 25, which is only a one level differnce.
There is just no justification for choosing Learning.