In my opinion, sudsy ammonia is superior to dish liquid. It is less likely to leave a film because it evaporates with the hot water. The reason you want to use hot water is because it heats the blade and that causes the solution to evaporate.

I would strongly advise against trying to use steel wool to clean the runners if you intend on inserting it into the scabbard. The chances of getting steel filaments caught in the runners is too great and those would further damage the blade. I suggest using a thin piece of metal wrapped tightly in a skin of an old T-shirt. You can get the metal strips at most hardware or hobby stores.

If you take down the dagger get yourself a Pflueger fishing reel wrench. They work perfectly and do not have to be ground at all.