So, I had this idea. Not strictly original, but still . . .
- Keep the lists divided by class, as they are.
- There are no additional costs for "cross-class" NWPs.
- Redefine the NWPs to make them broader in application.
- Each additional slot devoted to an NWP beyond the first, grants a +1 to the roll.
- If a task seems reasonable for someone with training, then no roll should normally be required.
Roll d20+stat mod (from NWP table)+class level (if NWP is from your class list) +/- situational mods
If the modified roll is 20+, the check succeeds. So, it's basically a Target20 type thing.
Here's what I like about it:
- Your character gets better at NWPs that are important to his class as he levels. He doesn't start out great at it and only improve slightly.
- If it isn't on your class list you won't be as good at it as a character who should be better at it. I don't like the idea that your fighter can spend slots on Magecraft (even if it is at double cost) and automatically be comparable in that skill to my magic user (assuming your fighter has a high INT).
There should be certain of the NWPs that aren't usable untrained. The remainder of the NWPs can be used untrained. In this case, if the NWP is on the character's class list, add the relevant stat mod, otherwise, the only mods are situational.
There it is, my big idea.