I think it is really nice and I want one most desperately. It could well be just that the decoration fits the form. The cross as a motif is not the exclusive property of "christianity" The use of a formal structured line in decoration is common. On this club the decoration is very bold and solid which seems to suggest a cross more than just following the form. Even after colonial and missionary governance, clubs would still be carried for minor tribal dispute and as part of general attire? This link is interesting, the first man struck dead is by a gun but used as a club. Could it be that by this time anybody who was anybody wanted to be seen with a gun? even if they had no bullets?
http://en.wikipedia.org/wiki/Malaita_massacre