I would have liked to see Gunslingers get their 75% worthless skilled made viable then given a second class, Artilleryman/Artillerywoman
The Artilleryfoo would use skills based on a few ideas:
1. Large AoE, high-damage skills that lose effectiveness the more people are in the AoE (The damage gets "spread out")
2. A skill similar to Rapid Shower (fast burst of damage on a target) with defence piercing/armor-destroying qualities to them.
3. Heavy one-shot damage with lots of cooldown with more exotic status effects or debuffs on hit (Think Full Buster but more interesting).
4. These skills would have drawbacks such as weapon breaking, high cooldown/SP cost, a cast time, or other things, making them situational-yet-powerful.
5. While the Gunslinger tended to focus on Rifles and Pistols more, the Artillery class would specialize more in Shotguns and Grenade Launchers. Of course, they could always continue to use the Gunslinger skills.
6. To compensate for having a second job, Gunslinger job level would go back to 50, and Artilleries would have 50 as well.
The idea being you set up your stage, get the appropriate weapon, then let loose and completely smash somebody in with one or two choice skills. In practice, inexperienced Artilleries would probably fumble a bit, use the wrong skills at the wrong time and have a giant neon sign that says KILL ME PLEASE as they suffer the penalties for the skills. Skilled artilleries, though, could easily be applied to shut down Paladins or High Priests's nigh-invulnerability.
