<div class='quotetop'>QUOTE (Nori @ October 1, 2007, 6:38 PM) [snapback]11435[/snapback]</div>
No. That's not why he's a shinigami. He's a shinigami, because the extreme amount of raw power that he has. You're somewhat confused though. It really isn't his sword that is beating anyone, it is all him.
All Shinigami don't have the ability to do bankai, because if they did, they would lol[/b]
That's what I'm trying to say lol. Kenpachi is only using his own power to beat the other guys without the help of his sword.
Yes, he has the ability to level up his sword. In the episode after the end of his fight with Ichigo he tried to talk to his sword but the sword didn't answer back. During his fight, Ichigo's sword partner said that Kenpachi's sword partner is in pain and it's scared of Kenpachi. So he has the ability to go to lvl 2 and even lvl 3 but he can't do it yet. Maybe in the future he can, but he has to do a little sweet talk with his sword partner. (note one of the latest episodes when the shinigami group (Captain Hitsugaya, Matsumoto, and the two other guys) have to talk to their swords)
And yes, all shinigamis have the ability to do bankai. They just have to learn how to get to it. Example, Ichigo didn't have a bankai before his fight with Rukia's brother. So, Yorouchi took Ichigo to Urahara to train Ichigo and make him learn bankai.