Whew! I thought from the title that you were looking to arm some bears with knives. That would be foolish, because bears are pretty fearsome to begin with.
I think what you would want is a large--really large-- fighter. Think bowie with a point. Wide blade for a large wound channel. And long.
Bagwell-style bowies, Cold Steel Natchez bowie, maybe the large SOG bowies, etc.
By the way, if you do find a bear in the woods brandishing a knife, you will probably need a gun.
Liberalism has failed humanity.