The build itself -
My main question is, is the kneeling shot worth it to go into Archer c2? The dmg and attack speed buffs seem pretty nice, especially if i can position myself behind the boss with it. Its mostly a pve build, im just hoping to make it good enough to work late game, not planning on doing min-maxing or anything like that.
Also questioning the rank 6 pick, cant really decide between rogue and falconer. Falconer seems pretty cool and i probably wont be able to position myself behind the boss all the time, so it seems to be more solid overall.
Lastly about stats, im planning on going mostly into str, adding around 30-40 con around lvl 80-110, but since if i happen to pass up on rogue for rank6, how much should i invest into dex, if at all?

After all, it really depends a lot on other stuff you get (accessories chants, gear, gems and so on).