Yah I doubt I would stand much of a chance using such a weapon, but it would think it would be better than nothing.
It isn't really for Bear hunting either, but mostly for when I run into Bears while hunting other game. Just yesterday while hunting Rabbits I ran into a single Black Bear on the unimproved road I was walking. I figured I would just give a holler or two and send him on his way. Well instead he came closer to get a better look! So I raised my bow above my head and gave a mock charge screaming. That finally sent him on his way, but it was the first Bear I have ever met that didn't turn tail when I announced myself.
I decided on a large blade after reading numerous stories of people saving their lives in Bear attacks with little more than hunting knives. In fact last year in Alberta a man actually killed the Grizzly that attacked him with just a knife. I know a blade won't save me from a mauling, but it may save my life.