I definitely agree about the special arrows, though. Marksman (or Scout, or whatever) doesn't really need a huge skillset in order for range-type characters to have decent versatility. Scoundrel, on the other hand, definitely needs more tricks, including more which aren't dagger-based. I feel the rangers just need barely enough to actually have to make choices (ex: can't use all available skills unless 5 ranks in ability), and not a whole lot more than that; Scoundrel, on the other hand, needs a lot more than it has now.
Let's say if I'm making a mod, I would definitely make Expert Marksman actually increase the effectiveness of the arrow - indirectly making it a requirement to have high Expert Marksmanship if you want those Special Arrows to be effective at mid to high level.
Imagine, if every rank on Marksman would increase Special Arrow effectiveness by 10% - That would actually reflect that this ranger is actually highly trained- and knows where to fire the special arrows to inflict the greatest damage / highest chance for the effect to successfully apply.
Add a new Talent - The Specialist Marksman (E.M Rank 3 required)
Every usage of Special Arrow costs 1 less AP.
4 AP Knockdown arrow from 15 meter. No Cooldown. That's something.
