Guys, we're talking about keris here, not ethnicity or race or anything else. There are paralells sure but its still apples and oranges. Humans can be defined by others but they can also define themselves. A keris is an inanimate object. It cannot define itself any further than its features communicate to us meaning and significance.
I would put to you that people in general assess the keris, as with most other examples including these cited by BluErf, based on the sum total off its parts. A Javanese blade dressed in Terengganu parts is a Javanese blade dressed in Terengganu parts. Why limit ourselves to such a simplistic notion that, because the blade is Javanese, ergo the keris is Javanese? Certainly we can grasp the complexities of a Javanese keris, dressed in Terengganu parts?
I would further argue that people will only define things based on what they know about them. In that sense my argument about walking into the Kraton was a bit unfair. After all they could not reasonably be expected to recognize the blade as being Javanese when they could not see it. And once they were assayed of the facts they would certainly be most willing to accept that the keris was in fact a Javanese blade dressed in Terengganu parts. Of course they would have probably have gotten bored and gone for coffee half-way through the explanation but hey that's real world and we're speculatin' here.
Also, Tom I'm afraid I don't quite buy your arugement about permanent (or impermanent construction). Its fair to say that in almost every case, a Javanese keris that has been dressed in Malay dress has been permanently modified - precisely because the pesi of a Javanese blade would almost certainly have to be shortened to fit a Malay hilt. Sure, you could re-dress the blade back in Javanese dress but I would also suggest that most Javanese would be appalled upon removing the hilt and discovering that the blade had been permanently disfigured.
I leave you all will a fun image of the excesses of parts sharing...let it be a warning to us all