[Autumn]

Sayakensa currently is a detriment to a Kensei no matter how you look at it, you gain some crit rate sure which is really good, but Crownbleeder+ also does practically the same thing and gives you bonus stats on top of that.

I think the payoff for having a cursed katana being that your autohits become Dark Damage is cool as heck, and should certainly stay in line with the weapon's theming, but I also think that changing your damage type to Dark more often than enough is a detriment, especially if you're unable to use Indignant Idol to shred off a bit of dark resistance.

Because Eresh isn't a Katana either, that item doesn't fit with it either, and as a result, there just is no way to make this item work in it's current state without actively inhibiting your build.

At the very least, please consider buffing this item so that it may shred off dark resistance, similarly to how Eresh functions as a dark damage sword, shredding off 10% Dark Resistance per Kensei autohit (Up to a cap of 30%) would be the ideal scenario for this item I believe, its a really cool item that opens up more Kensei 'sheath' options as well.