You are committing a common error in portraying the Māori and their culture as being crushed and suppressed by colonialism. Hapless victims. The reality of the interplay between missionary and Māori is far more nuanced than that and you a strong disservice to Māori in your portrayal.
I'd ask what basis you have for your assertions about the 'lost' definition of mana, when the definition of mana in the Māori Dictionary specificially states:
> 2. (noun) prestige, authority, control, power, influence, status, spiritual power, charisma - mana is a supernatural force in a person, place or object.
It goes on to explain how mana originates from the Atua and propagates down. It also discusses the close relation between mana and tapu. http://www.maoridictionary.co.nz/word/3424
However, I do believe that Maori history and cultural perception has been colored by Christian historians. This has only recently begun to be rectified by John Moorfield, and other authors who have contributed to the Maori dictionary, which is a relatively recent advance.
Currently it's used in NZ to mean prestige, but it's original sense was much broader - a tree that grows well has mana. Gods have mana. People get mana through (1) their heritage (i.e. high status families have more mana), (2) from other people i.e. we give a sportsperson mana because we respect their ability to kick a ball, and (3) via the group (e.g. if I'm part of a prestigious group, some of thir mana reflects onto me).
There's a good article on it here: http://www.justice.govt.nz/publications/publications-archive...
While the etymology is supposedly Proto-Oceanic, there's an interesting parallel with Kriyamana karma, particularly in the more modern usage of gaining/losing mana/karma through your actions.
I'd be very interested in any further explanation from fit2rule about the missionary influence on the term. What you say is plausible, but is it based on real sources or just your interpretation? Most Polynesian societies were not secular in the sense that the chiefs consulted with the priests who interpreted the signs of their deity and both acted accordingly. So the chiefs ruled somewhat by divine authority, and the social taboos were couched in religious meaning. So mana could have had a meaning of divine grace or chosen by the gods, yet a modern-day Hawaiian shaman did not explain it to me that way.
The abstract begins:
Comparative data are assembled to suggest that in Proto-Oceanic, mana was canonically a stative verb meaning 'be efficaceous, be successful, be realized, "work"'. Where mana was used as a noun, it was (and in most daughter languages is) not a substantive but an abstract verbal noun: 'efficacy', 'success', 'potency'.
[1] http://www.jstor.org/discover/10.2307/3629696?uid=3738032&ui...
Probably "reputation" is the best pakeha (western) equivalent to the concept