The "Brainwashes you." part of the description is supposed to imply that you can't use weapons because your "owner" has forbidden it. But it probably should be explicitly specified.you're talking about the dancer clothes especially the tiara right? that one that cause the entire you can't equip weapon thing. It's because it didnt have that function before, either Eccma slip up his finger somewhere or he forgot to put in the new description when he made those changes to the damn clothes that made it unusable.
Mind you, the official English translation is in major need of some TLC (text blocks with wrong names [but are correct in the CHT native language], excess files that don't exist in any other translations, etc...)