Ok, final reply to myself (haha):
- are there unique weapons beyond the ones on the store? I think I've gone through every dungeon and nothing.
- The tower's exit seems to lead to a square surrounded by stones. Any hint as to what I'm missing?
Yes, in Minima there is one weapon available that's better than anything you can get in the store. You'll have to talk with folks to get info on it and where to find it.
There's a switch that you passed earlier that you need to find. I believe there's also a clue about this that someone has someplace, but I confess it's been awhile so I don't recall where.