From every given skill you can made more basic skills.
Sword skill may be group of Striking, parrying, and deflecting. Furher, striking is skill made of diferent blows - strike in head, strike from down and a lot more. And we can continue with this.
Additionally when grouping skills into one, you can do it in dfferent ways. Like dodge can be part of sword skill, or light armor (in fact, maybe it is part of both). This what matter is how important in overal the skills can be. By joining skills into groups we obviously loose a lot, because in different situations, the group skill isn\'t fully accurate. But this keep things simple as we can found out how good we are by checking only few skills.
Also, we loose by making too wide groups of basic skills.
In effect if someone want to use different kinds of armor at one time, he/she will loose a lot, because skill light armor have nothing to do with medium or heavy armor. All three armor skills partially share some basic skills, but the fact that we don\'t train the basic skills, but the group skills, disallow us to use skills which we have to other related skills.
It is same with different kinds of weapons. They are all different and used in similiar way, but not the same. That\'s why someone who will specialise in sword, will know a bit about fighting with spear as sometimes you use sword the same way as spear.
And yes, dodge is skill, you can learn to avoid hits in different ways, practice it and train. You may call it passive when fighting, but the fact is, if you don\'t fight, you don\'t train it.
Also, i wanted to say, that currently the skill parrying is nonexistant, as training sword, don\'t let you to decrease damage into HP - Hit Points, not health points. It is difference which some poeple don\'t see. Loosing hit points, doesn\'t necessary mean you got hit in flesh. Loosing health points means exactly that you got hit and most certainly start bleding and die fast.
