Reading this story makes me think of that scene from the movie Predator where the Seargent encounters that Lord God Humongous pig at night, and proceeds to perforate him 9 ways to sunday. Kinda amazing what a well trained and conditioned man with a 12" or longer bladed knife can do when provoked.
Still, I believe this fellow here got darned lucky. The sow's big mistake was in giving the surveryor enough time to deploy his weapon. Had she been more experienced, she would perhaps have jumped him more unaware, and then had her way with him. As it is, it sounds like she was tentative until he armed himself and appeared to be more of a threat than she first considered, then she had no choice but to respond ex post facto.
I'd have been scratching my thigh in search of my phantom 44 if it had been me there. A knife would've been an afterthought.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)