So, how much maintenance is the K390 going to be?
You will need to wipe and oil it after every use if you do not want a patina on it. If you do not mind patina, then just the wipe after every use.
Sharpening wise, you will need to buy CBN/Diamond rods for the sharpmaker for best sharpening experience. With standard ceramics it will be a chore (if not impossible) if you somehow nick the edge even slightest. However, if you are careful with edge, a few pass on fine ceramics after every use will do the trick.
If you set your heart on K390 and do not expect to deal with organic materials to often (like stabbing people) go for it, but as a secret agent and mystical ninja, if you need to stab someone frequently, then go with VG 10
