I thought of this the other day. Why not introduce Faction skills? With one skill line in each. Three come to mind.
Faction Skills
Ranger
Bard
Necromancy
You join a faction and get access to it's skill line. Make it so that you can only be in one Faction at a time, but can respec out of it and join another if you like. Or make it possible to join all of them <shrugs> like the guilds. I don't know. If you can join all of them just add the skill lines to World Skills. Whatever makes more sense. Anyway it's just a idea. What you guys think?