Hi in the rules when discussing getting new traits, changing beliefs etc. it talks about “investing Artha” in them, and that it will be explained in the Artha section but it isn’t explained (or I keep missing it!)
So I understand tracking Artha for shade-shifting skills and stats / attributes and it’s easy to see that you clearly spent Artha on those things. But how do you spend Artha on a trait or belief and why track it? What is the result?
Thanks! 
Spending Artha on a belief/instinct/trait just means you spent artha on a test in pursuit of that belief, or as a result of that instinct or trait.
It is for the trait vote, in the older versions, spending better artha on beliefs and such let them evolve into better traits come trait vote time.
I believe in gold (away from books so if someone wants to cite a page number correcting me feel free), that is no longer formally spelled out and the trait vote is a bit more flexible in what level of trait you can get in a trait vote. Still the old guidelines (fate = character, Persona = Call on, deeds = Die trait) still have some value, and even if you don’t use them for the vote, tracking them can still have value in having a somewhat objective measurement about what things were important in your game.
Great thanks, I could have sworn I’d read something like that… I’ll bust out my old BWR book and take it from there, cheers!
The BWG Codex (p107-108, “Beliefs, Insticts and Trait Voting” section) mentions it as a loose guideline but merely as a suggestion to be ignored or not based on how much bookkeeping your players want to bother with.