mmm, not really, its not like the masters gives the keyblades, the keyblades choose it weilders and then they can go with the keyblade master, well i think that was the case with TAV, and the keyblades arent limites to one of each realm, there are 3 realms, and there can be many keyblades from each realm as weilders appears, and remember, roxas uses 2 keyblades, one is dark and the other is light, is what he says and Nomura stated this too.
Yeah, the world of light and darkness, inbetween, and "supposedly" the world in its present state (what ever that means, Nomura probably dropped that concept).
But Keyblades can only be of either Light, or Darkness. Meaning Keyblades are either predisposed to the Light side, or the dark side. A Key that acts that way is called the outer. The inner is a Keyblade for example, is of one constitution however, the wielder uses it in benefit to another constitution however, its powers dose not change. Mickey's Kingdom Key Darkside is a good example of that.
How those capable of wielding the Keyblade obtains their Keyblade is yet to be precisely determined considering how many ways it had happened.
It is highly speculated that Terra had something to do with Riku obtaining the Kingdom Key however, when Destiny's Island was in turmoil, Riku wasn't true to his heart (his heart was weaker) so, the Kingdom Key picked the next strongest heart in line, and that was Sora.
Mickey sought a dark realm Keyblade, so he gone through the darkness corridors to reach those worlds. He some how, instinctively managed to pluck a Keyblade. How he did that is unknown... Did he get chosen? Did he know he would get chosen by the Keyblade considering what was going on in the worlds, and the degree of his heart strength? He is assumed to be chosen by the Keyblade during the events of BBS, so did the same thing happen to him when he was in the world of darkness?
Riku's Soul Eater evolving in the Keyblade is also different than simply being chosen.
We also see things like Riku giving a Keyblade so Kairi can temporarily use. So it appears that you can be handed a Keyblade, and that you can wield it if your heart is strong enough. The Keyblade is still Riku's however, Nomura stated that there is a special meaning behind that transaction...
So, how a potential wielder ends up with the Keyblade exactly seems to stray a little. Were Terra, Aqua, and Ven simply chosen by the Keyblade (like Sora), or did their weapons (similar to the Soul Eater for the sake of discussion) evolve as they got Keyblades for their very special weapons? There's a bit of things we still don't know about in regards to a Keyblade appearing in the hands of those who are capable...