This question is actually spawned from a rather embarrassing personal blunder years ago, that was that when I had first begun to learning an heavily inflected language, I had made the mistake of assuming that if an article declined, then it carried enough grammatical information that the noun went undeclined.
Now the reason why I ask this is because it was natural for me -- different things are natural for different people, but I do declare that if it was for me, could it have been for another culture?
Because it has been requested, here is a made up example, using some Old English declensions mixed with Contemporary english:
Let's take the undeclined word King, it's article is þe. If the word is in nominative, the undeclined form, one says þe King, if it is plural, then a man says þa kings, if it is in dative, then it is, for singular, þæm Kinge, plural, þam Kingum, if it is accusative, then it is þone/þa king/kings.
So what I am asking is, is there a language that will, instead of declining the noun and making the article agree with it, will instead decline the article and leave the noun be, so instead of saying: Iċ geaf þam kingum þæt sweord, you would instead say I gave þam king the sword; this being done because the article carries the necessary grammatical information to tell you the gender and number of the noun King.
I felt that using "king" instead of "cyning" would push the point across a bit easier.