I am of course referring to Raksha in general. I have little knowledge of the Raksha on keris hilts.
Here is one aspect of Ganapathi Dyanam from the RUPAMALA - a 11-12 century silpasastra or instruction for workmen/artisans originating from Sri Lanka.
The Dhyana of the Three eyed Ganesha
I bow to the Vigna Rajah, distinguished by an elephant face, with sharp tusks, three eyes, a big belly, having the features of a Bhuta, adored by men and gods, of a red colour, a king of gods, son of Isvara.
Gaja vadana vicitram tikshna dantam trinetram
Brahadudaramasesham bhuta rupam puranam
Amara nara supujyam rakta varnam suresam
Pasupati sutamisam vighna rajam namami
Note the reference to
bhuta rupam i.e. the
appearance of a Bhuta. Refers back to the earlier discussion of 2006 on this forum where Bhuta Nawasari as a Rakshasa king had ben discussed.