After playing a healer merc for quite a long time, I decided to check out the PvP viability of arsenal (with full WH mods & set bonus for dps) , and I too was disappointed with the "glass cannon" aspect of the AC. Sure, it can be a lot of fun and great numbers against pugs who don't prioritize kills or focus target, but terrible dps and survivability against even the slightly-above-average premade with some WZ experience and awareness.
Second, not sure why they took away the 2nd KB, what about it screamed "nerf me!" to the devs? In a dps spec, the loss of this ability became immediately apparent as something that would be a little more helpful in a 1v1 against a melee class instead of a root. Now it would seem that it's only utility is to stop some LoS escape artists from getting away from your melee core, or when having to be the LoSer (pun intended) healer merc doing some pillar hopping.
A few other thoughts/suggestions with this class:
1. Allow dps specs to have an improved shield ability similar to "Undying Rage". The 25% dmg reduction prolongs death by about .1 secs against good players. At least let us go out with a "bang" after 5 secs.
2. Add talented stun/root on the only 1 KB we have (similar to snipers/slingers) instead of a larger KB distance which is extremely counter-productive against jumpers anyway.
3. At least make the knockback for Rpunch like ~1 feet like the assassins/shadows sweeping slash or w/e.
Feel free to rip this post apart - Servers are down and I was bored.