A spell list to choose from would be great, it can be used as a guide for players and facilitators on what spells a character can learn.
I do not know if it would be a great idea but I think classes should have a bit more of a spotlight. Classes helps players define their characters' role in the party. Each class might have 2 or 3 skills (exclusive to this class) that they can choose 1 from.
Class Skills work a bit differently as they might require a set amount of gold to be spent at a specific location for it to improve.
Something like this:
Knight
Choose one;
Guarded - +1 to maximum armor point, have 1 armor point when not wearing armor (+1 per skill improvement)
Cover - once per battle, choose to take the damage to be dealt to an ally (+1 more use per ability improvement)
Character can improve or change skills at forts or bastions. Changing skills will reset all improvements.
Improvement Cost: 100g × (next ability level + 1)
This might lock player characters to a certain playstyle but their presence in the party would be clear.
But just because a class system exist shouldn't restrict player choices.