Employee of Magic Research Institute:
The figure of a pig's smiling is carved on Apiga. It is traditionally said that the figure of a pig's smiling will bring wealth and luck, so this is very popular to those who start a new work at times like this when a new year begins. Especially it is very popular among adventurers who prepare a new adventure in a new year. Thus, they give Apiga as a gift to each other because its symbolic meaning.
I'm not sure if Apiga will really bring you luck, but we're very fortunate that Apiga is considered as a symbol of luck since we have to ask adventurers for help. We can receive help in adversity and adventurers can obtain wealth and luck -- this is an example of beautiful mutual help.