I recommend grinding a flat down the center of the blade making sure that both sides are flat and parallel. This is a good job for a surface grinder, but you can do it on the platen or disk if you are patient. It doesn't have to be a wide flat and in fact it shouldn't be especially the further away from the ricasso area you go, but you will need the flat to get a crisp straight center ridge. Once the flat is established then I would grind the profile of the blade. I do this by eye and check the profile frequently by holding it with a light in the back ground so I am seeing just the silhouette. Subtle changes in the line can be picked up if you look at what you are doing.
Once the profile is established, then you are ready to lay out the grind lines. Spray the blade completely with Dykem or fluid lay out die. The first task is to find the exact center line of the blade. If you have done a good job of profiling we can assume the point is in the visual center so you begin by finding the middle point on the ricasso. Scribe a light line connecting the center point of the ricasso to the point of the dagger. I use a brass scribe for this so I don't leave a scratch. Next layout the termination points for the bevels. A handy tool for this is a small square. I have two that are under 3" and perfect for lots of jobs. If the edges of your ricasso area are parallel, you can just lay the square up against the blade and scribe the line at right angles to the center line. Follow this line by marking across the thickness of the ricasso and match it to the other side of the blade. Check to make sure that all scribed lines match. Take your time with the layout and you will avoid problems later on. Do this on both sides of the blade and then sight it from all angles to make sure the lines match up and that there is no obvious misalignment.
I begin my grinding by roughing out the bevels with a coarse grit on an eight inch wheel. Be careful not to take off too much stock, but enough so that the flat grinding will be minimum. Be careful here not to go anywhere near the center line, concentrate instead on the flats to the edge. Next I move to a platen on the belt grinder. I use a Burr King running on about half speed. Beginning at the ricasso begin your plunge at the ricasso just before your final mark. Work edge up at right angles to the platen.
A word about platens here. It is helpful to grind the platen so that it is narrower than the 2 inch belt width and radius the edges so that you can walk up into it with a flexible belt. I true my platen with a straight end making sure that it is flush with the top contact wheel. I like to adjust the height so that I am working with my elbows locked into my side and the blade is held with both hands at just above belt height.
When you grind on a platen you must be sure to lock your arms in and move the blade by shifting your body weight. This is critical to maintaining control and takes practice and attention. If you tip the blade into the belt the cut will dive toward the edge, if you tip it away from the belt it will climb. The primary grind is a straight cut right off the end of the blade. At this point you do not grind in the point, this is the secondary grind and because it tapers it has to be feathered in after the primary grind is established.
Watch the cut you are taking, if you find you are climbing too fast and approaching the centerline adjust the angle of approach. Since you have removed much of the metal on the wheel, you do not need to lean into the grinder here. Take lighter passes and watch how it is cutting. I stop my rough grind within a quarter inch of the center line. If you go by the center line on one side you can't pick it back up without regrinding a fresh flat and starting over.
Set the plunge cuts now and with a light touch feather them into the flat. Get them as close as you can with the coarse grit belt. You will make up minor differences with finer grit J-Flex. At this point you want to make light passes watching the center line and trying to make the top of the cut straight and crisp. This can be nerve wracking and demands focus, so I take a break if I find I am tense or if my mind is wandering.
I don't attempt to finish the blade completely on the grinder and when I have done as good a job as I can on the belt sander, I leave the finishing and final approach to the center line for the files and hand tools.
Hopefully you haven't crossed your scribed centerlines while on the machines, you should be close though. Moving to the bench vise use a bastard mill file to make the final approach to the centerline. The way I use the file is to grasp it on both ends and draw it back and forth at right angles to the direction of the blade. You may want to refresh the layout die to see the high and low points as you work, make sure you can still see the center line. This method is called draw filing and you can established true flats by being careful to keep the file from rocking. This is very aggressive and you can quickly remove metal from the blade. Work carefully up to the centerline on both bevels.
You have to determine how you want to fair in the transition from the center line to the termination of the bevels at the ricasso. If you run the centerline straight back to the flat of the ricasso you run the risk of cutting past center and you have no margin in an area where you need some room. I recommend leaving a slight "V" flat from the ricasso before you join the center line. Approach this transition slowly and watch it develop being sure to make the curve equal on both sides. Look at photos of daggers and examine this area to see different approaches to this problem.
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Since this area is the beginning of the transition from the blade to the guard and handle, it is often used as part of the design element and can be quite elegant. The line of the knife will visually flow through the guard and shaping the ricasso area will help to establish the line. Notice how the ricasso on the Warenski example above is ground to establish that line reducing the width of the blade at the back of the ricasso to blend with the ferrule and handle. This creates a pleasing and subtle curve and unites the handle and blade lines. In the Loerchner example, he uses a long ricasso transition and then cuts a transition bevel that mimics the transition to the ferrule and handle. This is elegant and emphasizes the symmetrical quality of the piece.
