No need to "avoid magic" with an archer.
Some magic skills align perfectly with an archer.
Furthermore, all skills can be combined with all other skills - as i just said above the game is made for any kind of jack of all trades - ACTUALLY.
Additionally, you dont need to have any skill points in the Marksman skill to use a bow and those special arrows.
If a character has enough dexterity to wield a bow - that character can use it and the special arrows.
Archery - Marksman skill is not necessary for that at all. Its just that a character build made for that will be more precise and a bit more effective at it.
- fact: you cant really miss with special arrows. They always hit. (and that should be changed)
