This is a question about Sol's ethnicity. While he is a born and raised American, since he designed Zessen so that it can only be activated and wielded by those of Japanese blood, could this possibly mean that he is part-Japanese as well? Or was that a fail-safe feature created to prevent letting just anyone use it should it be stolen?
You bring up an interesting question, though it has little to do with Frederick’s ethnic origins.
The Zessen, while still considered a part of the OutRage as a whole, was built around the concept of forming Dimensional Barriers and is able to manipulate Wind and Sound.
Anji Mito has been seen using it to enhance Mizuha’s Kotodama (or spirit “voice”, a voice generating Ki energy).
The Japanese have a strong connection with Ki based on their bloodlines alone… but the reason Zessen is ‘activated’ via that bloodline is currently a mystery.
Sol has not explicitly stated the reason he allowed the Zessen to fall in to the hands of the Japanese… and it might very well be that the “bloodline restriction” was added later by someone else (possibly the Conclave).
But one thing is certain… the Japanese appear to have a strong connection to the Backyard, because of their Ki-based bloodlines… it was for that reason that “That Man” targeted Japan and used Justice to destroy it, in order to sever the connection.
The Zessen itself was later used to form a “barrier” around the Japanese Colony to prevent contact from the outside world…
Considering the “threat” that the Japanese pose as a potential “conduit” of the Universal Will… that might be a possible reason the Zessen was so specially designed to function in this way, as an Anti-Backyard device.
So you could say that the Zessen was “programmed” to activate and form a barrier in the presence of Japanese bloodlines as a failsafe to prevent contact with the Backyard. A failsafe that Frederick might have designed with consideration to the events that occurred during the Dawn of Revival and the destruction of Japan. Of course, that’s speculation.
No one actually considered the idea of using the Zessen as a weapon except Anji Mito! Fans are rather unorthodox weapons, as you may know. Of course, while Anji Mito is accused of “stealing” the OutRage… in reality it was entrusted to him by the elder of the shrine who had kept the Zessen when it was “lost” during the Crusades.
Currently it’s unclear if the Colony still has any sort of barrier around it in place of the Zessen… but likely that is the case, since Johnny makes a remark in GGXrd to the effect that those who enter the Colony cannot technically leave without some means or token.
Dr. Faust warns Johnny to keep May away from the Colony at all costs due to “something” that may be happening there in the near future.
As for Anji Mito’s whereabouts… only time will tell what he’s been up to the past 6 years since he began his journey with Baiken to observe “That Man’s” activities.
Chances are good Sol will be looking for Anji to recover the Zessen from him in the future, since he’s already obtained the Flashing Fang from the Conclave (and still possesses the Firesealed Sword).