Yes, words change meaning, especially when they're imported across language boundaries. Originally mana DID mean something like spiritual power, and is heavily linked to terms for thunder, lightning etc.

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...