[secretperson]

There is no chance for arcane spell failure unlike D&D type games but, as sector24 said, encumbrance plays a big role. Fatigue will make you easier to hit and make critical hits possible and if it gets high enough will knock you unconscious and possibly kill you if it keeps piling up.

I haven't played Maverni at all to know what you are talking about with the druids, but some commanders when given certain items can become quite nasty as they can cast buff spells then go into the fray.

Again, like sector24 mentioned, there are various types of items and armor with no encumbrance- for example; the robe of invulnerability or lightweight scale mail.