First, I don't think that this nice dagger (daga) is Visayan. The peened through tang let me think that it coming from Luzon but let it to the experts from where exactly. Also the beautiful stiched leather scabbard shows that it is from Luzon. First quarter last century?
But so the handle couldn't be a stylized twin Bakunawa IMHO. Niece piece!
Regards,
Detlef