Question on progression after unlocking 6th character

SPOILER warning, this is right after unlocking 6th character >!Monoco!<.

So, right at the train station in the snowy area, you are always given warning by the guys there that "hey don't go the other side, it's dangerous icy mountain area".

But I decided to clear it up, it was fun & challenging indeed. Got crazy weapons & pictos too. I thought it'd be fine since they don't block the player to try.

Fast forward now, so many areas later, turns out all the stuff I got from there still overpowers all the new enemies?

So, anyone else got similar experience? Have you guys intentionally unequip pictos/weapons just to fix being overequipped/overlevelled accidentally?