Hi
Strongest Melee weapon with only 1 forma needed, provided you have [Chromatic Blade] augment on [Excalibur]

Empty slot is due to the Overframe not showing up [Exalted Blade] stance that gives extra 10 capacity for free
I put [Berserker Fury] in there, same effect as [Primed Fury] but cheaper and saves a forma

With maxed out combo you have both guaranteed Critical and Electricity status proc
Tennokai is fantastic for Bosses
In crowds allows to spam Slash Dash with guaranteed Electric and Slash procs

Why no condition Overload? - You at BEST gonna only do 2 status procs which is 80% x 2; it's not worth it
If you really have to do priming on level cap enemies - its much easier to just settle for Viral spread

Otherwise if you want to use it to kill bosses more easily, get a dedicated boss killing gun, instead of making Exalted Sword worse