Iconography of balinese hilt, question

[Jacob]

Does anyone know the significance of the mask on the backs of the heads of antropomorhic balinese keris? Here are some examples.

[nechesh]

Hi Jacob. I believe it is Garuda and is there as a guardian spirit for protection.

[DAHenkel]

They are called Garuda mungkur. They're like having eyes in the back of your head.