A build with an empty slot for Surging Blades (9 Drain).

[Surging Blades]:
[Surging Blades] is an augment for Aquablades that allows you to throw a single Aquablade like a [Glaive] if you already have Aquablades active. The thrown blade does damage with a guaranteed slash proc, and its strength increases by 10% with each tick of damage applied by ANY blade. With max duration, you can stack that thrown blade to have very high damage, dealing thousands of damage within seconds due to slash.
This augment also eliminates casting cost while riding Merulina (Exalted K-Drive). By abusing that no cost cast, we can drop efficiency to completely raise ability duration (and strength) on the Aquablade to build stacks for longer.
The small range buff makes it easier to build stacks for [Surging Blades], as well as letting thrown blades' AoE [Reach] past corners a tad bit further.

[Yareli]'s Passive and Secondary Synergy:
While on Merulina, [Yareli] can use only her secondary weapon, as well as any of her other abilities. [Yareli]'s passive grants +200% Critical Chance on sidearms if she has been "moving" on Merulina for at least 1.5 seconds. Moving is in quotes because it doesn't mean movement, it just means a direction is held. You can "move" into a wall and keep the crit buff.
[Pistol Amp] and Arcane Precision are used in this build because of its synergy with [Yareli]'s passive, doing extra damage on sidearms. Of course, [Coaction Drift] is used here to boost [Pistol Amp] even more.

Mod Replacements:
[Overextended] can be replaced with [Stretch] to increase your base Aquablade damage from 104 damage to 149 damage.
[Carnis Carapace] can be replaced with any survivability mod. Alternatively, it can be switched out for [Streamline] to reduce initial energy cost. You would need to rely on Merulina's damage reduction and your blades' slash proc staggers to act as CC and protect you from damage, though.
Coaction Drift is not strictly needed, just a nice-to-have. You could forgo having [Coaction Drift] to replace [Carnis Carapace] with most mods, even with the D polarity.
You can replace the Aura with [Steel Charge], removing the need for one D polarity. It would also mean you can put whatever exilus you would like to, rather than [Coaction Drift]. If you really wanted to, you could forma for [Corrosive Projection], but I don't find it worth using up an Aura Forma just to fit meta. [Steel Charge] and [Pistol Amp] work perfectly fine for this build.

TLDR:
High duration to build stacks. Low efficiency to abuse Surging Blades energy cost elimination.

Forma setup synergizes with https://overframe.gg/build/287428/