Believe it or not, a skilled kendoka is unstoppably fast. you can mitigate the force but if one comes at you with a broomstick an intent, you're gonna get hit. And while striking the armor is for safety in Kendo, that translates to broken wrists, skulls, ribs and collapsed throat in unarmed combat. They may need to think real hard before using it for swordwork, but it is phenomenal stick skill
Yes.
Not as such. They often fall under knives. Although its still reasonable suspicion, and possibly felonious carrying of a martial arts weapon. As far as generalities go, of course. Specifics are a no-no.
concealed? There is almost no way to carry a sword concealed at the hip. Or did you mean something else?