Instead of generic sources and behaviors that all classes pull from, each class will have a specific lis of behaviors categorized by level. This will allow closer balancing within classes.
There can still be more generic sources that are recotegorized as versatile sources.
Maybe each source also has a tag associated with it. So you could pick a healing feature for cleric but select a source that provides some sort of additional damage and gain the Strike tag on that feature.
These should probably be tied to the specific subclass they are made for. Future subclasses will have their own sources and behaviors.
You can then have feat like Domain Initiate for cleric for example that would allow access to feats from other domains as well as their sources.
I wonder if keeping behaviors universal would be easier.