Thomas,
especially in proper names, the "actual meaning" of the combination of various kanji is really not so easy to define. i think it's commendable that you've taken an interest in japanese, but this particular question is probably not worth spending too much time puzzling over. still, here's some information to satisfy a bit of your curiosity:
heian - peace; peacefulness, tranquility (also the name of a period in japanese history)
heiwa - peace; harmony (the nuance here seems to be "freedom from conflict")
antei - stability; steadiness; security
each of these terms contain two ideographs. the word antei itself has nothing specifically to do with "the mind". HTH.
Jeff Hamacher
Those who speak do not know,
Those who know will not speak ...
So I guess that means I don't know a thing!