Just now I noticed this fascinating topic!
I think that 5 images of the swastika symbolize 5 types of happiness - longevity, wealth and prosperity, body health and peace of mind, virtue and a peaceful end in the family circle. These were very important concepts in ancient China. Most often they were symbolized by 5 bats around the "shou" character 夀 "longevity, immortality" (a bat in Chinese "fu" is a homonym of the happiness). This mark is quite common on Chinese weapons.