I seem to recall a lot of desire for gun kata characters back on Live when dual pistols were first hinted at. A melee version of dual pistols with good close range AoE damage and some actual melee attacks (pistol whipping enemies) could be doable. I'm just spitballing here, so I haven't thought out any power names, but...
T1: single target, Melee Light DMG (animation: War Mace -> Pulverize, but with pistols in hand instead of a mace)
T2: narrow cone, Close Range Moderate DMG [two targets max, one for each bullet] (animation: DP -> Dual Wield)
T3: single target, Melee High DMG (animation: War Mace -> Crowd Control, but with pistols in hand instead of a mace)
T4: cone, Close Range, Moderate DMG [max targets normal for AT] (animation: DP -> Empty Clips)
T5: Reach for the Limit (as the Martial Combat blaster secondary power)
T6: Confront / Taunt (animation: Staff Fighting -> Confront/Tauntbut with pistols in hand instead of a staff)
T7: single target, Melee Superior DMG (animation: Super Strength -> Punch, but with pistols in hand instead of a mace)
T8: single target, ranged High DMG (animation: DP -> Executioner's Shot)
T9: PBAoE Moderate DMG to everything in Close Range (animation: DP -> Hail of Bullets)
I'll let someone else play with the numbers specifics. I tended to err on the low side with damage to make up for the set having a little bit of range to it. I think Reach for the Limit is a good substitute for a Build Up effect because it plays to the whole idea of the gun kata style, looking for vulnerabilities in foes' stance & positioning and having a chance to gain to hit and damage bonus with each attack you make for a short time.
Okay, someone name these powers, tweak as needed, and wrap it up. I want to see it in the next build on the test server. 😁