So based on the data gathered, we can be 95% certain that the average drop rate of the traitstones is within + / - 3% of the figures in the table.
Another 800 samples before we can get to + / - 2% (but I’m not sure being any more accurate is worth it).
It is clear that you may as well be farming the moon if you’re trying to farm arcane traitstones for a base level Epic or Legendary character. I think the better strategy may be to gather Glory, and use it on the the weekly bundle (such as Arcane Blood) this week.