Hello Henri,
best and shortest explanation you will find here: "Tangkis- a means of warding off, or a shield; a blade is said to have pamor tangkis when
it carries a different pamor motif on each of its blade faces, and this is considered to be a talisman against black magic."
It is a citation from a site of a member here but by some reason don't want to provide the link.
BTW, nice blade!
Regards,
Detlef