When we administer blessings we are commanded to use olive oil. A quick bit of research through the scriptures, Church magazines and Conference proceedings yielded basically only the reasons (a) we’ve been commanded to do so; (b) the ancients did it that way; and (3) it is the purest kind of oil. It is advised that if you do not have pure olive oil (and its purity is important and emphasized) do the blessing without.
Yet in much of our richest symbolism, we understand the reasons for the symbol. In the sacrament the bread stands for the body of Christ, the water the blood. It is very specific and well understood what these symbols refer to. Yet even in that holy ritual the substance can be substituted, if we understand and honor the referent. We all know the story of potato peels being used at the end of WWII. The symbols point to the atonement. The form the symbols take is not the important thing and the material symbols can be substituted.
This does not seem to be true of priesthood blessings. It has to be olive oil or nothing. Why? What is the olive oil pointing to?