why would you use [Galvanized Crosshairs] over [Galvanized Shot] on a status secondary with a subpar crit multiplier?
Radiation is the other top choice for an innate element. You could also swap to Corrosive with the [Jolt] mod but I don't own it currently.
For Arcanes, Merciless is a bit of a waste since this weapon doesn't have a conventional reload and doesn't have spare ammo. If you're going to use Merciless just use the [Kuva Nukor] and you'll get better results out of it. Dexterity makes this weapon a better primer than the [Nukor] ([Condition Overload] has a cap of 3 statuses so while [Nukor] can achieve more statuses it won't increase your damage, and using it as a primer for a Primary weapon with Galvanized Aptitude/Savvy also makes dexterity the ideal choice thanks to the holster speed) while Deadhead gives it easy maintenance on its damage buff and also providing extra headshot damage which can be very nice at times. just use Cascadia Flare. Nothing else competes.
[Ruinous Extension] is pretty much objectively the best exilus mod for this weapon as most of the other options do literally nothing for it.