Lately I've been working on a set of houserules I've dubbed Trailfinder. One of the goals has been overhauling the skill system. When it comes to the Knowledge skills, I'm leaving them mostly intact, but giving them more immersive names. So far I've renamed Knowledge (Arcana) to Thaumatology and Knowledge (Religion) to Theology, and simply removed the 'Knowledge' from Dungeoneering, Engineering, Geography, and History. Knowledge (Local) got removed and incorporated into a new skill called Streetwise. That leaves Nature, Nobility, and Planes. The only things I've been able to come up with are Nature Lore, Heraldry, and Cosmology. Does anybody have any other suggestions?
Will you be splitting up K: Nature in regards to plants and animals, or will you keep them linked?
For K: Nobility, I don't think Heraldry is appropriate. Heraldry is a very specific subset of knowledge, and would work better as a Profession, in my opinion. I would recommend replacing K: Nobility with "Culture".
Definitely keeping Nature as-is. I completely agree about Heraldry, I just couldn't think of anything. I can't come up with a word that means 'the study of nobility'. I may consider doing away with Knowledge (Nobility) altogether, and rolling its functions into other skills.
You could rename Knowledge (nobility) to Intrigue, and then in addition to its normal uses, allow it to be used to spread rumors. This would give a very interesting boost to an otherwise-lackluster skill. And I think it makes sense - those who know more about the lives of the nobles can more easily defame them, and those who are skilled in defamation are likely to know about powerful people.
You could merge Nobility with History or with Diplomacy. After all, if you're going to allow it to spread rumours and what-not, it seems like it should be part of the Gather Info skill, which in Pathfinder is Diplomacy.
Alternatively, merge Diplomacy with Nobility, but remove Gather Info from it and add it to your Local/Streetwise skill.
You could simply merge Planes and Religion, particularly if you go with the idea that your study of the gods and their servants and workings would also include their habitats.
After all, if you're going to allow it to spread rumours and what-not, it seems like it should be part of the Gather Info skill, which in Pathfinder is Diplomacy.
Well, the in-game precedent for spreading rumors actually uses the Bluff skill. But, it requires a specific Rogue talent. Converting Knowledge (nobility) to Intrigue would reward players to invest points into it, whereas otherwise very few players would ever put more than one rank into Knowledge (nobility) except maybe for RP reasons.
And which is why I suggesting merging it with Diplomacy. I think that talent is a waste of space, frankly, but it rather suggests that only a 10th-level rogue or higher with that specific talent knows how to spread rumours. I'm now suddenly scared of the average fishwife.
Thanks for your help, guys! I ended up incorporating the functions of Nobility into History and Streetwise. Streetwise has taken over Diplomacy's 'gather information' function, as I feel like it fits better there. I also ended up incorporating Planes into Religion (or Theology, as I'm calling it), as the planes in my setting are more metaphysical in nature and mostly inaccessible by mortals (outside of death). That just leaves Nature. 'Science' doesn't really have the right feel or connotations to me, particularly in a fantasy setting. I've settled on Nature Lore for now, but if anybody comes up with anything better it would be greatly appreciated!
Just keep in mind that the 'Knowledge' prefix actually does have some mechanical effect as well. 'Renaming' it away might muddy up some other traits/feats/abilities that affect 'knowledge' skills.