Welcome to the forum, Jonathan! There is a ton of information on this forum, so when you are unclear on something, look it up, and chances are, you will find what you are looking for.
I very strongly suggest that you keep it simple, especially since this is your second blade. The clay idea, sounds like a recipe for failure to me. Depending on the size of the blade, you may be able to do a full quench, then a soft draw temper with a torch heating along the center, and letting the heat run out to the edge. It would have to be a pretty wide blade for it to work, though. My recommendation is just to do a full quench in oil, and a full temper in the oven. You will not be battonning a dagger, so you really don't need to worry about blade failure, for its intended purpose, if you successfully heat treat it. Why are you wanting to do a water quench? You will be dealing with temperatures in the thousands, and water can only heat to a maximum of 212 degrees, so not much difference in the long run! I suggest you stick with the methods that have been established and are proven to WORK. Good luck with it. I hope it all works out well for you.