What is the meaning of "li'Kdoshim Asher ba'Aretz"?
Rashi: For the sake of Kedoshim who died, and are buried in the ground. They went in front of You in truth!
Radak #1: This is like "l'Ish Kamocha Rish'echa" (Iyov 35:8). Due to my love for You, I love them, for they are Kedoshim, and I benefit them.
Radak #2: I am not worthy of Your good. Rather, the Kedoshim are worthy of it.
Radak #3: This is connected to the previous verse "Amarta la'Shem
What is the meaning of "v'Adirei Kol Cheftzi Vam"?
Rashi: These are the mighty ones, that all my desire is in them, and all my needs are done for them.
Radak #1: Those who have greater hearts than others, and are better than them, my desire is in them, to benefit them, for they guard Your Mitzvos.
Radak #2: "Adirei" is not Samuch. We find like this - "Chalonei Shekufim" (Melachim I, 6:4), "Nit'ei Na'amanim" (Yeshayah 17:10) and similar verses. Kedoshim and noble ones, that all my desire is in them, to love them and go in their ways.
Malbim: An idolater thinks, in these Kedoshim (gods on the land) are the Adirim (powers) that rule over all my desires. They attributed to them all powers of the Nefesh - man's desires and natures. One is appointed over love, one over quarrels and war. They said that man does not have choice; the gods force him to love or hate, be merciful or cruel - each god according to its charge. This is known from the idolaters' songs.