Rapier heavy attacks inflict a guaranteed slash proc. The focus of this build is to maximise the slash proc damage, which scales well into endgame as it ignores armour.

Essential Mods

Sacrificial Pressure - This is used over Prime [Pressure Point] as this it adds an extra 55% crit rate to [Sacrificial Steel] (110% with heavy attacks). The extra boost just pushes the crit rate on heavy attacks into guaranteed Orange Crit territory, which gives more stable damage output.

Sacrifical Steel - 550% crit on heavy attacks is no joke

Berserker - Highest attack speed boost. Can use a quick standard attack to build up initil stacks, which often happens naturally anyways when switching from primary/secondary weapons into melee.

Amalgam Organ Shatter/Killing Blow/Corrupted Charge - Standard set for heavy attack spam. Extra wind up speed and damage.

Primed Reach - Extra range too useful to pass up.

Life Strike - there are very few mods that can increase the damage of slash procs (no elemental mods, no IPS mods). [Life Strike] is great utility option, but can be replaced.