Yes, I'd wager Alexiette was a combo of
Alexander (or, in this case, the feminine form,
Alexandra) or
Alexis (which was originally male, however) and the name suffix -ette. -ette itself has no meaning, unfortunately, but you can see a list of names ending in -ette here:
http://www.behindthename.com/php/search.php?terms=*ette&nmd=n&gender=both&operator=or.
It's a pretty name, though nms (I don't really care for combined names like these, sorry).
Miranda