Spiral Slasher - my theory.

You likely know about the spiral slasher, a removed weapon in PSIV. It’s a slasher that probably would’ve been available late game, but was removed, and this is my guess why:

It can put enemies to sleep, and that could include ALL enemies, and the game devs likely thought this would be too overpowered, so they added a new slasher, the moon slasher. It does more damage, but its sleeping affect only works when used as an item.

That’s my theory.

Yes it's a good theory BUT it dépends at which rate this sleep power was effective or not !