May Hashem bless you and guard you. May Hashem illuminate His countenance toward you and endow you with grace. May Hashem lift His countenance to you and establish peace for you. The blessing of the kohanim is called a bracha meshuleshes, a three part bracha. In reality there are six brachos. Why is it called meshuleshes and what is the logical progression of the three brachos?
The opening bracha provides for monetary success and protection from mazikin (Sifrei). These are not two separate brachos. Rather, the second half is a protection from the potential perils of the first half.
You increase silver and gold for yourselves and everything that you have will increase. And your heart will become haughty and you will forget Hashem (Devarim 8:13-14). This scenario describes the ruination of numerous individuals and communities in the history of Am Yisroel.
In our own time we have witnessed many decent, observant persons and/or families whose lives and/or marriages have been ruined by the temptations and trappings of great wealth. Torah observance and moral uprightness, which governed happy, wholesome homes of modest means, are too often discarded by the adoption of a lifestyle made possible by, and associated with, extraordinary financial success. These are indeed riches hoarded by their owner to his misfortune (Koheles 5:12).
These are the mazikin, the damaging side-effects of monetary blessing, which "v'yishmerecha" guards against. Hence, it is not a separate blessing, but rather a preserving of and protection from the potential perils of "yivorechecha."
The second bracha is the blessing of Torah. May he give you the light of Torah (Bamidbar Raba 11:!3). As we say in "sim shalom": for with the light of Your countenance You gave is the Torah of life. The blessing of Torah and of spiritual greatness is critical to the very essence of a Jew. Yet even this bracha requires protection.
And you shall love Hashem your God, that the name of Hashem become beloved through you. One should read, learn, and serve Torah scholars, and his dealings with people should be in a pleasant manner. What do people say about him? Fortunate is his father who taught him Torah. Fortunate is his teacher who taught him Torah. Woe unto people who do not learn Torah. The person who learned Torah, see how pleasant are his ways, how refined are his deeds.
But one who reads, learns, and serves Torah scholars, and his business transactions are not conducted faithfully, and whose manner of speaking with people is not pleasant, what do people say about him? Woe unto that person who learned Torah. Woe unto his father who taught him Torah. Woe unto his teacher who taught him Torah. This person who learned Torah, see how perverse are his deeds, and how ugly are his ways (Yoma 86a). This is the terrible sin of chilul Hashem (Rashi).
One who is blessed with the privilege to learn Torah can cause a great kiddush Hashem or the opposite. An ignorant Jew who is dishonest or impolite cases a small chilul Hashem. A talmid chacham who is dishonest or impolite causes a much greater chilul Hashem. In that case, his very learning is not a blessing but a curse. Therefore, after the kohein gives the bracha of Torah, he hastens to add "viychunecha", may He endow you with grace, namely in the eyes of people.
Popularity is not necessarily good. But in this context, it allows the bracha of Torah to cause kiddush Hashem. Hence, it is not a separate blessing, but rather an extension of, and a protection from the potentially disastrous chilul Hashem consequence of the bracha of Torah.
The angels said before Hashem, it is written about You, "Who does not show favor - lo yisa panim" (Devarim 10:17), then how do you show favor to Israel ("yisa Hashem panav ailecha")? Hashem answered, and shall I not show favor to Israel? For I require birchas hamazon only if they eat and are satiated. Yet they are stringent and say birchas hamazon even for a kezayis (Berachos 20b).
This stringency is different than other rabbinic enactments. It refers to one who is so poor that he only has one kezayis to eat (Tanchuma Naso 10). Yet he favors Hashem. Not only does he not complain, but he even recites birkas hamazon. Since he favors Hashem, Hashem, favors him in return (Rav Eliyahu Gutmacher 20b).
Thus, the last of the three brachos blesses a poor person who is meticulously observant. Presumably the bracha is wealth to go along with Torah. This is the progression of the three blessings: wealth, Torah, and a combination of both.
Yet even this great bracha of material and spiritual wealth can have a downside. A rich man enjoys wealth, and a scholar enjoys Torah. One who has both blessings is often beset with inner conflict. Should he focus on learning or on financial matters? Sometimes this conflict precludes appreciation and enjoyment of either of the brachos. Therefore the kohein adds "may He establish peace for you". This does not mean a peace with other nations or other Jews. Rather, it means an inner peace which enables a recipient of spiritual and physical blessings to enjoy both. Hence it is not a separate bracha, but a protection against the conflict which can arise from the combination which is the first half of this bracha.
In sum, there are only three brachos in ascending order, and each can turn into a curse. The second part of each of the three brachos is meant to guard against the potential negatives of the first half. It is not a separate bracha but a means to preserve the blessing of the preceding phrase.
The words of birchas kohanim are part of our daily communal tefila. Let us internalize the critical lessons of these blessings so that we be worthy of receiving them.