I took a class in Greek but it was long ago so I'm not up to speed. But my NASB reads:
"Now may the God peace Himself sanctify you entirely; and may your spirit and soul and body be preserved complete, without blame at the coming of our Lord Jesus Christ."
The translation or reading you are using includes the word whole. No problem, I'm just pointing out the difference because I don't see that word (whole) in the NASB. But, I would think the adjective applies to all three. In the sense that Paul is saying that God will sanctify "you" entirely. You meaning in your entirety - your whole spirit, whole soul, and whole body.
That's not presented as beng the final word but I hope it helps. I can do word studies etc. but the sentence structure rules etc. are beyond my ability right now.
"Doc"