Looking at Pre-Essentials 4th Edition classes, it seems like they map out like this:
Three trained skills:
- Defenders: Battlemind, Fighter
- Striker: Barbarian
Four trained skills (one max be fixed — e.g. required Religion for a divine class):
- Defenders: Paladin, Swordmage, Warden
- Strikers: Avenger, Monk, Sorcerer, Warlock
- Leaders: Ardent, Cleric, Runepriest, Shaman, Warlord
- Controllers: Druid, Invoker, Psion, Seeker, Wizard
Five trained skills (one is fixed):
- Striker: Ranger
- Leaders: Artificer, Bard
Six trained skills (two are fixed):
- Striker: Rogue
I'm a bit mystified by the Battlemind, Fighter, and Barbarian getting only three trained skills. Is there a particular reason for this? Something about their other class features or the relative value of certain class skills over others?
(I'm more interested in how the skills play into class balance than "designer reasons.")