[Chaos]

Bear in mind that you still need to connect with this weapon to land the effect, assuming they don't laugh it off with Steel Aura. If all you're doing is taking some Water-slinging spell build, slapping this weapon on them and throwing them at someone, you're not only forcing them to give up a equipment slot for it, they're also dealing very poor damage with just about no critical, assuming the target completely dumps evade. You'd need a two-man party, minimum, for a mage to truly abuse this effect, which is less of an issue than a one-man 'apply and destroy' build.

I would only do the following to the weapon's effect:
1. Decrease the effect's duration from 4 turns to 2 turns
2. Potentially lower the effect from 40% to 35%, to start