Sorry Kai Wee, but i respectfully disagree. I don't mean to suggest that dress is unimportant. That is certainly not the case. But the iron is always the MOST important part of the keris. Dress will be changed by time and circumstance, but the iron remains. If the owner a a keris pusaka falls on hard times he might be found to sell off the valuable parts of his dress, but the keris itself would be the last thing he lets go of. I would personally always give due respect to the empu of such a keris by referring to at as being from it's place of origin first rgardless of which culture it is dressed in. To me this is the only logical way to properly classify these weapons in a way that makes sense.
Why did Hang Tauh find it necessary to go to Jawa in search of a keris? He must have thought much of the skills of the Javanese empus. Do we then disregard their work and skills. IMO, Taming Sari would be a Javanese keris in Peninsula dress. I would have to respectively disagree with your Malay friends though i understand their sense of nationalism.