These abilities, generally in the upper-end, require pre-requisites to be able to learn them, with these requirements not necessarily coming from the same skill line.
Skills do not have Secondary Skills as there were in Heroes IV, instead, there are anywhere between 3-5 abilities that are classed under a certain skill. The Heroes V system is a much more dynamic one, giving the hero a choice from 2 skills and 2 abilities. However, this is one of the few likenesses to the Heroes III skill system. The skill levels will also revert back to a Heroes III guise, disregarding the two new levels of Master and Grandmaster introduced by Heroes IV. In addition to the Primary Skills, there are also Morale, Luck and Mana, which can be improved in different ways by varying abilities. The main 4 returning: Offense, Defense, Spell Power and Knowledge.
Information confirmed by various gameplay videos has confirmed that at least the Primary skills will work in a similar fashion to Heroes III.
