Ian,
Thank you very much for your help in possibly identifying the proper name of the flower with four pointed petals seen on this dagger. Then by pointing out that "People believe that the blooming santan can ward off evil spirits and is a good luck plant" could also easily explain why these flowers are seen carved into the scabbards and hilts of many of the Philippine edged weapons that we see. Now if we could identify another flower with four more rounded petals that is also considered to be good luck or protection from evil it would explain the other flower found on the above dagger.
Best,
Robert