The point of having a blade with a monomolecular edge is that a simple piece of monofilament is flexible. It becomes quite hard to apply enough mechanical force in order to get it to cut. As such, the blade itself provides the mass and structure that allows you to provide mechanical force through the blade. It´s the simple difference between hitting someone with a string and hitting someone with a stick, the string is nearly incapable of cutting armor no matter how sharp it is due to the lack of kinetic energy. The composition of the blade itself makes it incredibly sturdy, meaning that it won´t break in battle. Being suddenly disarmed would be a severe problem for a swordsman such as Kami no Kage.

We have not yet reached the point in our knowledge of the brain that we would be able to build a device quite on-level with the suit harnessed by Kami no Kage. However, we are rapidly reaching that point. Furthermore, I view SOLDIER and the PURGE as having access to the highest level of technology available, above what we know right now. As you have access to magic and awesomeness through that, I retain the right to travel into the near future, and use cool gadgets from there. 

Here's my case for your character being overpowered:

You are capable of instantly killing any character in the country, without them having any logical chance at response. From kami no Kage to Mo to Gabriel, you could instantly kill any of them. The requirements for you activating this ability is that it's night-time, and that you get a couple of posts to increase the darkness, something that can only be countered by killing your character, which becomes progressively more impossible as time goes on. The idea of having a character that's more powerful in the darkness is awesome, and I would agree that he should be really hard to kill during the night. But making him capable of defeating the entirety of SOLDIER, as well as every vampire (oldblood or no) in the space of a single night, is a TAD retardedly overpowered.

Keep in mind that it is heavily implied that you have a number of other abilities you have not even used yet, and are thus even more dangerous than has been seen up until now.



Also, I had no plans for the dude. He was there to look cool, and die. I had planned to have him die fighting Lady Mo, but I would have been fine with you jumping in and killing him. That is not the issue here.