Not related but a pierce mod would make range on knives a much more desirable stat.
An alternative to the fan of knives could be a chain effect? Where the knife jumps to the nearest enemy and then you could have more chains for this effect vs more pierce for the fan effect.
Kyougou
I've added the chain effect, but kept the fan. It feels and looks cool

It keeps going until full range is used up, so +range is much better now.
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Burst of frost/dagger storm is what trivializes things once you get a few upgrades. Then any combination of haste, defense, heal (i tend to take the duck heal instead of regen) will make things easy provided you keep an eye on casters. I tend to bum rush them to freeze them. The axe and saw are just gravy, so I only upgrade them when nothing better presents itself. I wasn't impressed with darkness, poison, or lightsaber penguin, so never chose them. I don't have good replacement suggestions but will give it some thought.
The only real threat I find is from casters. Change those fireballs to snowballs, increase fire rate (1.5 maybe), and make them immune to frost (for lore reasons).
Edaw
Burst of frost, dagger storm and duck heal are all... well, nerfed (the N-word). Also, casters can no longer be frozen and they cast more often. Other options were buffed instead, though. Poison was completely redesigned to be blizzard-like now. Somewhat same damage and slow, but very different in usage. Darkness removed, for now.
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Path of exile handles crits well. (it does also have the crit/crit damage problem) but it also smartlydid something else. Crits apply ailments. freeze, burn, shock, stun.
That would work great here imho. If crits applied a stun, pushback, or bleed effect for example. its way more interesting then just double dipping damage scaling.
Caliane
You are right, plain crit is not that interesting, at least in this implementation. I am still looking for an improvement... Maybe crits could fill up a bar (particles flying from enemy to bar) and "something" cool could happen when full. PoE solution sounds complicated. I'd like something that can be communicated in one sentence, and also not too much work

Zap/shock that chains might be cool, though... Chain lightning.
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Anyways, thanks for the feedback, was really motivating.
Balancing has come a long way (in the beginning it's about buying upgrades, but skill becomes more and more important) , so right now I'm looking at things like colors / theme / setting. Are pirate ducks really optimal here? was just using what I had available. And a short story from chatGPT. Stuff like that.
And sound effects... work work.