[A. G. Maisey]

Further to Sid's illuminating revelation, it might be of interest to understand that the name of this hilt type in Bali is "bebondolan".

"Bebondolan" means "like a bondol". In Balinese, the bondol is a type of bird that in English would be called the "White Headed Munia", in Javanese it would be called the "Manuk Bondol Haji".

The word "manuk" is a Javanese word for "bird" and is also recognised in Bahasa Indonesia, however, in colloquial usage in both languages it can be a euphemism for the male sexual organ.

The Balinese word for "bird" is "kedis", the word "manuk" seems not to be known in the Balinese language, but it is recognised in Bahasa Indonesia usage in Bali.

Keris terminology is full of euphemisms, we can run through the entire collection of words that are applied to various parts of the keris & a very large number of these words are euphemisms.

It seems to be possible that in attaching a phallic symbolism to the Balinese bebondolan hilt, Sid may well have revealed another such euphemism:-

bebondolan > bondol > manuk > male sexual organ.

Below is a photo of a bondol bird.

EDIT

I have been asked why I did not progress my comment to the logical conclusion. Well, I stopped where I did because I thought that the rest was obvious, and to add to what I had written was a bit like driving a panel pin with a four pound hammer.

But I've been convinced that I should bring out the one hand sledge, so, with additions:-

bebondolan > bondol > manuk > male sexual organ > lingam > Siwa (Shiva)

using this understanding, it seems clear to me that the the bebondolan hilt is in fact a symbolic representation of Siwa, this is quite fitting, because the wilah of the keris itself can be understood as a lingam, so we have Siwa providing protection against evil to the keris, and thus indirectly, through the keris to the custodian of the keris.