(My english not that good, sorry for my mistakes)
Thats my best [Nikana Prime] build. Thats great weapon is one of most powerful melees in warframe. Great status and critical chance, a lot of slash damage, perfect [Nikana].

This build provides you to use [Epitaph] of panzer vulpaphila to slash realy strong enemies. Thats my epitaph build. You can have about 7 statuses with that (4 with area attack)

[Relentless Combination] allows you to use a lot of heavy attacks (if you use heavy attack, damage some mobs with 12x combo to get combo right after heavy attack).

Now about spring-loaded blade. Range of melees is underrated. Nikana prime has realy a lot of damage, so with range you can kill more enemies. [Spring-Loaded Blade] gives you +2 range attack. Primed reach gives you +3, but it provides 2 more forms and platinum for primed mod, so [Spring-Loaded Blade] is your best option.

[Sacrificial Steel] give you 220% of crit chance, [Blood Rush] gives 440%, but on heavy attacks, [Sacrificial Steel] also gives 440%. Thats a lot of crit chance, heavy attack has 305.2% of crit chance
(28 + 28(440%([Blood Rush]) + 440%([Sacrificial Steel]) + 110%(gladiator might)) = 28 + 28 * 990%(9.9) = 28 + 277.2 = 305.2%)

Critical multiplayer is 5.9, with 300% crit chance it is 15.7 (3(5.9-1)+1 for red crit), combo final multiplayer is 12x, [Condition Overload] base damage buff is 0.8 7 = 5.6, viral buff is 4.25, stance heavy attack boost is 500%. Base damage is 990 for heavy attack.
990 6.6 = 6534([Condition Overload])
6534 15.7 = 102 583.8(crit damage)
102 583.8 12 = 1 231 005.6(combo multiplier)
1 231 005.6 4.25 = 5 231 773.8 (viral buff)
5 231 773.8 * 5 = 26 158 869 (stance boost)
slash status damage is just 0.35 of that final damage (might be about 7 847 599 per tick)
(All mobs are steel path 120 lvl)
I realy don't know why that is not true, maybe i forgot about about fraction bonus or something like that, but my damage was 7 278 170 per tick.

I have tested that about 5 times, idk why is that so. (i used Kuva Heavy Gunner Eximus as most heavy enemy in my simulacrum, demolysts have awful damage formula)

I also had 106% roar, that might increese slash damage 4.24 times ((1 + 1.06) + 1.06 * (1 + 1.06)), and yes, its great

With status chance 151.2 (28 + 28*4.40) you have 50% chance to do over 43 and over 86 millions of pure damage, that ignores armor (with 70% roar it shoud be

I also like to test damage on steel path demolysts, and there is what i have:

If you use roar, damage is greate (that difficult, because every 5 seconds it disables all abilities in 6.5 meter range, but you can do that):