Well, Hugh Glass, an old time mountain man, shot one once with his Hawken when they surprised each other in the brush. The bear wasn't too impressed with the ball, so he attacked and severely mauled Glass. Glass had some kind of big butcher knife or Green River skinner or some such large, simple blade on him, and succeeded in killing the bear. Very nearly died from his wounds, though.
If it were down to a blade and a large bear for me, I'd want one of those big japanese spears with a sword blade on the end of the pole. Or maybe a boar spear, with a big long blade. And twelve or so friends also similarly armed. Or one guy with a .375 H&H....