Hashem blesses us with His shining face as we say in our tfilla כי באור פניך נתת לנו ה' אלקינו תורת חיים ואהבת חסד - with your shining face you gave of the Torah of life, a love of chesed etc. Through this bracha our face shines as well, as it says about Moshe כי קרן אור פניו בדברו אתו - His face radiated when Hashem spoke with him. We too can merit a glowing countenance as did Moshe Rabbeinu.
Afterwards the Kohanim say ישא ה' פניו אליך - Hashem should raise his face to you - sometimes the light comes from above based on our level, however the generous blessing Hashem bestows upon us through Birkas Kohanim is that we are blessed according to the level of HASHEM Himself. This leads to shleimus and spiritual perfection - וישם לך שלום.
SWEEET!!!
[Mei Marom page 31]
