It's cool. Now that I have a simulator, I just found out that you can only choose 1 from one of the 2 Bow Master skill. ;-;
Extension Arrow master of Charge Shot master. URGH.
If you choose EA as your main attack, your final skill is Revolutionary Ballista. Which emits forceful arrow to the front after summoning a huge bow, while shoot more arrows to nearby enemies around the huge arrow.
If you choose Charge Shot instead, you'll get Pinpoint Shot, which is just continuously shot 16 forceful shots of arrows in a flash.
Both have same CD in PvE. But if you like PvP as well, PP have lower CD (75sec) while RB have 90sec of CD.
GAH. Now I have to choose wisely.