Sorry, missed one...
Steel does matter in a fighting Bowie. A blade that breaks when struck by an opposing weapon won't do you any good. The sound of your blade ringing like a tuning fork after being struck by an opponent's knife will probably be your death knell. If it vibrates in your hand, throw it away, sell it, or send it back for a refund.
Well I suppose this is true if you are fighting someone with a metal pipe or a baseball bat. But in this situation, a bowie knife will probably lose to the pipe or bat. If I was in a knife fight, I would choose the longer weapon.
As long as the steel is heat treated properly, it really should not matter what steel is used to make the fighting bowie. The Hell's Belle's stainless is treated properly and will absorb shock like a true fighting knife should. If it was approved by Mr. Bagwell himself, it should hold up just fine.