You can equip it, but it does nothing below 5 Will. The stats won't get applied (not even the dodge penalty) and you can't use Hypnotize either.
Thanks for clearing that. It's definetly a nice boost and a good reason to choose JKK for any character meeting the 5 WILL requirement.
I don't know; I have 5 will on this run and I dont have any other saves where I cant test it.
Thanks for replying anyway, it's nice of you. Also, it reminded me of having my abandoned save (with 3 WILL), so I could test it myself if I was not so forgetfull to think of this and lazy.
EDIT: Got it to the point where the merchant opened up and after checking, the lines on the info sheet of the item get grey and they do not apply. I don't know why I preferred to see it with my own eyes, but that's the case.