A weapon invented a few years ago in District Serre. Rather than a tool of physical destruction, the Mentalscape allows one to enter the world of another's soul. Here they can see the world allegorically as the victim would.
The Mentalscape was banned outright in the Confederacy, which of course means that it's highly coveted. On the other hand, the Mentalscape is still legal (but highly controversial) in Murakami, because it was used to take down Locria Seastar, the chair of finance in Teichmueller Centre, who was long suspected (and finally proven, via Mentalscape) of laundering money used to smuggle weapons to Bradamante. After being caught, she resigned her post and fled the country the next day.