Hello Apophis,
Your model looks great. I am a novice but here is my attempt at your blade.

I duplicated the edge line and moved it up to create the top edge of sharpened area.

then I attached it to the tip and some point where I want the sharp to stop near handle side.

Then I extruded all the lines except the sharp edge.

This left a "box" for the sharpening.

at the point closest to the handle, there is a small Z level line. I swept this using the 2 curves as rails.

Then I planered the back curves.

This created a nice looking sharp but I cant get it to Boolean to the other to make a solid. Maybe some other input as this is where I always fall apart. I'll also look at it more.

[EDIT] Ok, I got it to Boolean, I wasnt picking my bottom surface. Seems this is a pattern for me to work on! I would also like to work the tip area as this transition is odd.[EDIT]