Dear Penangsang,
You are right.But in order for the keris to "reveal" itself to a wiseman or magus, it has to be strong enough, just like semar said. Otherwise it is impossible for it to accomplice that task.
And I was told that the "resident" inside is not something invited "in" to stay, but the sum of the thoughts,intention, and (part) of spirit of the maker.So when you "communicate" with a keris, actually you communicate with the spirit of the long dead empu..freaky!!
george